JP6511434B2 - Method of treating arsenic and compound containing arsenic - Google Patents

Description

  The present invention relates to a method of treating arsenic, and more particularly to a method of treating arsenic that can be used to treat copper ore containing arsenic.

  In recent years, in copper mines operating around the world, copper ore to be collected is mainly primary sulfide ore, iron, sulfur and other impurities increase, and copper grade tends to decrease. This results in increased copper concentrate production costs for dry copper smelting.

  Among the impurities in copper ore, the most problematic is arsenic. Arsenic, depending on the form of its presence, is extremely harmful and has few applications in the industrial sector, so most need to be disposed or stored in a stable form.

  Therefore, the buy and dry type smelter has given a certain limit (usually about <0.3 mass%) to arsenic in the copper concentrate to be purchased. When the mine side exceeds the limit, it is common to pay a penalty to the smelter side according to the excess amount.

  Therefore, from the viewpoint of mines, efficient treatment of sulphide ores containing a large amount of arsenic is an important concern for cost reduction and mine life extension. On the other hand, from the viewpoint of the buy and dry type smelter side, it is likely that it will be necessary to cope with copper concentrate containing a large amount of arsenic in the future due to the depletion of high quality ore and tight supply and demand of copper concentrate.

  JP-A-2009-39666 (Patent Document 1) discloses a method of treating arsenic in which the obtained crystalline compound is coated with a resin after the arsenic-containing compound is formed into a compact crystalline compound particle form with a small amount of moisture. .

JP, 2009-39666, A

  However, in the method described in Patent Document 1, there is a problem that the preparatory adjustment for adjusting the arsenic-containing compound to be coated with the resin to a predetermined form is complicated and the processing cost becomes high. In the case of long-term storage of the arsenic-containing compound for several years and several decades, the coating resin itself may also be degraded and elution may occur gradually.

  SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a method of treating arsenic that can be processed into a stable form suitable for long-term storage and storage in a simpler method, which is contained in copper ore containing arsenic.

  In order to solve the above problems, the inventors of the present invention have intensively studied and found that copper ore containing arsenic is roasted to extract volatiles containing arsenic from copper ore, and the volatiles are subjected to a predetermined treatment. Furthermore, it is found that the elution of arsenic can be suppressed for a longer period of time as compared with the prior art by performing the predetermined treatment to further increase the density of volatiles after the treatment and processing it into a more stable form. The

  In one aspect, the present invention completed based on the above findings is a roasting step of roasting arsenic ore-containing copper ore in a non-oxidizing atmosphere and separating it into chalcopyrite and volatiles including arsenic sulfide. Heat-treating the volatiles obtained in the roasting step in a non-oxidative atmosphere to melt the arsenic sulfide in the volatiles, grinding step of grinding the volatiles after the heat-treating step, and the grinding step And re-melting step of heating and re-melting the volatiles in a non-oxidizing atmosphere.

  In one embodiment of the method of treating arsenic according to the present invention, the remelting step comprises heating volatiles at 200-250 ° C.

In another embodiment of the method of treating arsenic according to the present invention, the remelting step comprises heating the volatiles so that the density of the volatiles after remelting is 1.5 to 3.0 g / cm ^3. including.

  In yet another embodiment, the method of treating arsenic according to the present invention further comprises adding sulfur in the heat treatment step.

  In still another embodiment of the method of treating arsenic according to the present invention, in the heat treatment step, the sulfur is contained so that the mass ratio (S / As mass ratio) of sulfur contained in volatiles to arsenic is 1.2 or more. Including adjusting the content of

  In a further embodiment, the method of treating arsenic according to the present invention further comprises adding an anti-aging agent in the heat treatment step.

Another aspect of the present invention is a solid arsenic-containing compound comprising arsenic and sulfur, wherein the arsenic concentration is 1 to 40% by mass and the density is 1.5 to 3.0 g / cm ^3. It is a compound.

  According to the present invention, it is possible to provide a method of treating arsenic which can treat arsenic contained in copper ore containing arsenic in a more convenient manner and in a stable form suitable for long-term storage and preservation.

It is a flowchart which shows the processing method of the arsenic concerning embodiment of this invention. It is an example of the microscope picture showing the property of the heat processing thing obtained at the heat processing process. It is a photograph which shows the appearance of the volatile matter (heat-treated material) processed by the heat treatment process. It is a photograph which shows the appearance of the volatile matter (heat-treated material) processed by the heat treatment process. It is a graph which shows the evaluation result of As elution amount of the arsenic containing compound obtained by volatilization, heat processing, and re-melting processing.

  In the method of treating arsenic according to the embodiment of the present invention, as shown in FIG. 1, a copper ore containing arsenic is roasted in a non-oxidizing atmosphere to form chalcopyrite and volatiles containing arsenic sulfide. Heat treatment step S2 for heat treatment in a non-oxidative atmosphere to heat the volatiles obtained in the roasting step S1 to be separated and the roasting step S1 to melt the arsenic sulfide in the volatiles, and volatilization after the heat treatment step S2 And a re-melting step S4 for heating and re-melting volatiles after the grinding step S3.

The processing object of the present embodiment is a copper ore containing arsenic. Specifically, for example, arsenopyrite (Cu ₃ AsS ₄ ), tetrahedral alumite (Cu ₁₂ As ₄ S ₁₃ ), or a copper concentrate in which copper ore containing these arsenic is mixed can be used. The ore is not limited to the above copper ore, as long as it is an ore containing arsenic other than these copper ores and which can be treated by the two-step treatment described below.

For example, the grade of copper concentrate mainly composed of arsenopyrite which can be used in the present invention varies depending on the grade of coexisting pyrite (FeS ₂ ) and gangue components, but typically 15 to 35% by mass of copper And 3 to 15% by mass of arsenic.

  In this embodiment, the copper concentrate is preferably predried at a temperature at which the mineral species and grade do not change. Usually, when drying copper concentrate with high temperature air, the temperature of the copper concentrate at the dryer outlet is about 90 ° C., and the moisture content of the copper concentrate is 0.5 mass% or less.

-Roasting process S1-
The dried copper concentrate is roasted at 550 ° C. to 700 ° C. for 10 to 60 minutes under a non-oxidizing atmosphere. For example, nitrogen gas is used as a gas supplied to make the inside of the apparatus non-oxidizing atmosphere. The control of the treatment temperature and atmosphere in the roasting step S1 is the conditions necessary to convert the copper concentrate containing arsenopyrite ore to arsenic sulfide, chalcopyrite or the like, and the reaction time is a residue of unreacted arsenoic acid ore. It's time you don't need it.

In the roasting step S1, the formation reaction of arsenic sulfide in copper concentrate follows the following equation (1) or (2). If pyrite and the like are contained in a large amount in the original concentrate, S added in the equation (1) is compensated by S generated by decomposition of pyrite in the treatment temperature zone as in the equation (3) Because it becomes unnecessary.

4Cu ₃ AsS ₄ + 12FeS + 2S → 12CuFeS ₂ + As ₄ S ₆ (1)
4Cu ₃ AsS ₄ + 12FeS → 12CuFeS ₂ + As ₄ S ₄ (2)
FeS ₂ → FeS + S (3)

  The roasting step S1 is performed using, for example, a rotary kiln. As shown in the above formulas (1) to (3), the roasting produces a sulfurized compound containing arsenic, and the produced arsenic compound volatilizes at a vapor pressure according to the temperature, and is removed from the raw material copper concentrate Be done.

  As a result of the roasting treatment, from the raw material copper concentrate, a calcined ore mainly composed of chalcopyrite and cubanite ore, and an arsenic compound (arsenic sulfide) which is volatilized and recovered, and a volatile matter containing elemental sulfur are obtained. In the temperature range of 550 ° C. to 700 ° C., the ratio of chalcopyrite of chalcopyrite and cubanite of pyrite ore, the amount of copper sulfide ore such as chalcopyrite and chalcopyrite included before reaction, the amount of pyrite included before reaction, and Change depending on the amount of pyrite

  Since As sulfide and elemental sulfur volatilized in the roasting step S1 are in the form of gas, they are cooled in a non-oxidative atmosphere, solidified, and recovered. FIG. 2 shows an example of a photomicrograph of the collected volatiles. The recovered volatile matter contains particulate particles of about 10 to 15 μm in diameter, and has a two-layer structure of an inner layer 1 and an outer layer 2 different in As grade.

  The inner layer 1 of the volatile particles is composed of a layer containing about 30 mol% of arsenic and about 70 mol% of sulfur. The outer layer 2 of the volatile particles is composed of a layer containing about 5 mol% of arsenic and about 95 mol% of sulfur. That is, the volatiles composed of particulate particles obtained in the roasting step S1 have a two-layer structure in which the outside of the inner layer 1 containing a large amount of arsenic in the particles is covered with the outer layer 2 containing a large amount of sulfur.

-Heat treatment process S2-
In the heat treatment step S2, the volatile particles shown in FIG. 2 are further subjected to a heat treatment in a non-oxidative atmosphere to melt the arsenic sulfide (arsenic sulfide) in the volatile material, thereby removing the arsenic elution of the volatile material. Reduce more.

  For example, nitrogen gas is used as a gas for making the inside of the heat treatment system non-oxidizing atmosphere. The treatment temperature of the heat treatment step S2 is preferably 200 to 600 ° C., more preferably 250 to 400 ° C. When the processing temperature is lower than 200 ° C., the arsenic sulfide in the volatiles may not be sufficiently melted, and the reduction effect of the arsenic elution amount may not be sufficiently obtained. If the processing temperature is higher than 600 ° C., the heat-treated product may not be recovered because hydrogen sulfide contained as arsenic sulfide in the volatiles is gasified and volatilized.

  The treatment time of the heat treatment step S2 varies depending on the treatment temperature, but it is preferable to carry out the reaction for at least 30 minutes or more, more preferably 50 minutes or more, in order to complete the reaction. Is preferred.

  In the heat treatment step S2, it is preferable to add sulfur to volatiles. This is because the volatilization amount of sulfur increases and the concentration of arsenic in the volatiles increases as the processing temperature in the heat treatment step S2 increases, so that the elution suppression effect of arsenic due to the reaction of sulfur with arsenic decreases. . For example, when volatiles having an S / As mass ratio of 3.0 are treated at 400 ° C., the S content in the volatiles volatilizes and the S / As mass ratio decreases to about 2.4, and at 500 ° C. When treated, the S content may be volatilized to reduce the S / As mass ratio to about 1.2. As a sulfur source to be added, elemental sulfur is preferable in terms of handling. Sulfur may be added before the heat treatment step or may be added during the heat treatment step.

  In the heat treatment step S2, it is necessary that the mass ratio of sulfur contained in volatiles to arsenic (S / As mass ratio) is 1.2 or more, more preferably 2.3 or more, and still more preferably 3 or more. It is preferred to adjust the concentration of sulfur and arsenic in the volatiles by adding sulfur accordingly. If the S / As mass ratio is less than 1.2, the elution reduction effect of arsenic may not be sufficiently obtained even if the heat treatment treatment time is increased.

  The upper limit of the S / As mass ratio is not particularly limited, but as the S / As mass ratio is higher, the As elution suppression effect can be obtained by heat treatment for a short time. On the other hand, if the amount of added sulfur is increased too much to increase the S / As mass ratio, the As elution suppression effect does not change significantly, but rather the excess sulfur content because the sulfur is excessive to arsenic. Post-processing may be required, resulting in cost increase. Therefore, the upper limit of the S / As mass ratio can be about 6.

In heat treatment process S2, you may add the anti-aging agent of rubber | gum other than elemental sulfur. This can suppress the elution of arsenic from the arsenic-containing volatiles for a longer period of time. As the anti-aging agent for rubber, for example, any one or more kinds of anti-aging agent selected from monophenol-based, bisphenol-based and polyphenol-based can be used. The addition amount of the antioxidant is preferably 0.2 mol / m ³ or more, more preferably 0.4 mol / m ³ or more, and more specifically 0.2 to 2.0 mol / m ³ .

FIG. 3A is a photograph showing the appearance of the volatiles (heat-treated product) treated in the heat treatment step S2. The heat-treated product is collected as a bulky columnar substance in appearance. The arsenic grade of this heat-treated material is 12 to 15 mol%, and its density is about 0.6 to 1.5 g / cm ³ . Since the sample is expanded by the heat treatment step S2, this heat-treated product is about half the density of pure pure arsenic sulfide. Although this heat treated material can be stored as it is, when the density is low, the specific surface area increases, so the contact area of the heat treated material with the external atmosphere (for example, air or liquid) increases, and elution easily occurs. There is a case.

Grinding step S3, remelting step S4
Therefore, in the present embodiment, the heat-treated material processed in the heat treatment step S2 is pulverized, and the pulverized heat-treated material is again heated and remelted to increase the density of the thermally treated material. An example of the remelted material is shown in FIG. 3 (b). The pulverizing method in the pulverizing step S3 is not limited to a specific method, and can be carried out by a conventionally known method. For example, the operator may crush using a predetermined tool, or a crusher may be used.

In the remelting step S4, the pulverized heat-treated product (volatile material) is heated in a non-oxidizing atmosphere using nitrogen or the like to melt the arsenic sulfide in the heat-treated product. The heat-treated product is preferably heated so that the density of the heat-treated product after remelting is 1.5 to 3.0 g / cm ³ . The processing temperature of the heat-treated product in the remelting step S4 is preferably 200 to 250 ° C, and more preferably about 220 to 250 ° C. If the treatment temperature is lower than 200 ° C., the heat-treated product may not be sufficiently melted. When the treatment temperature is higher than 250 ° C., part of the sulfur contained in the raw material is volatilized to expand the sample, so the density may not be increased.

The remelted product (sulfur-containing compound) obtained in the remelting step S4 is a solid arsenic-containing compound composed of arsenic and sulfur, and has an arsenic concentration of 1 to 40 mass% and a density of 1.5 to 3 It is .0 g / cm ³ . By storing the remelted product, preferably in water, it is possible to store and store the arsenic contained in the copper ore containing arsenic in a stable form for a long time.

  Hereinafter, the present invention will be more specifically described by way of examples, but the present invention is not limited thereto.

Example 1
As a raw material copper concentrate, a high As grade copper concentrate of 21 mass% of Cu grade, 23 mass% of Fe grade, 38 mass% of S grade, and 6.8 mass% of As grade was used. The main mineral composition characterized by X-ray diffraction (XRD) and electron beam microanalyzer (EPMA) for this high As grade copper concentrate is 11 mass% of chalcopyrite (CuFeS ₂ ), pyrite (FeS ₂ ) 42mass%, enargite _{(Cu 3 AsS 4) 36mass%} , was gangue component (SiO _2, etc.) 11mass%.

  When 100 g of this copper concentrate containing arsenic was predried and then roasted at a processing temperature of 650 ° C. in a nitrogen gas atmosphere, as shown in Table 1, the concentrate containing chalcopyrite containing almost no arsenic It could be separated into (burn concentrate) and volatiles containing 33% by mass of arsenic and 64% by mass of sulfur.

  The volatiles obtained in the roasting step were cooled and solidified to be recovered, and the S / As mass ratio of the volatiles was 2.3. The volatiles were heat-treated at a heat treatment temperature of 280 ° C. for a heat treatment time of 30 minutes in a non-oxidative atmosphere to obtain a heat-treated product. The obtained heat-treated material was pulverized, and the pulverized material was heated at 240 ° C. for 10 minutes under a non-oxidizing atmosphere to obtain a remelted product.

(Example 2)
Single sulfur is added to the volatiles (S / As mass ratio of 2.3) obtained in the roasting step of Example 1 so that the mass ratio of S / As in the volatiles is 4.1, and monophenol system is further added. An antioxidant (2,6-di-t-butyl-4-methylphenol) was added at 0.5 mol / m ³ , and heat treatment was performed under a nitrogen gas atmosphere at a treatment temperature of 280 ° C. for a heat treatment time of 30 minutes. The obtained heat-treated material was crushed, and the crushed material was heated at 240 ° C. for 10 minutes to obtain a remelted material.

(Dissolution result)
The elution amount of As was evaluated by the elution analysis (TCLP) of soil contaminants in the United States Environmental Protection Agency (EPA) with respect to the volatile matter, the heat-treated material and the remelted material obtained in each step of Example 1 and Example 2. . In this elution analysis, volatiles, eluates and remelts were crushed to make the particle size smaller than 9.5 mm (0.5 to 5 mm), and the sample was treated with deionized water, acetic acid or acetate buffer as an elution solvent. Liquid is used, pH is 2.88, solid-solid ratio is 20, temperature is 22.3 ° C, shaking method is rotary shaking and 30 rpm, shaking time is 18 hours, pressure filtration of solid-liquid separation (0 Elution analysis was carried out as (.6 to 0.8 μm GFF filter used). The results are shown in FIG.

  As shown in FIG. 4, the elution amount of As decreased as the roasting, the heat treatment step, and the remelting step were performed. In addition, in any of Examples 1 and 2, in the finally obtained remelted product, the elution amount of As could be reduced to 1 mg / L or less.

(density)
The density of each of the heat-treated product and the remelted product of Example 1 was measured, and the density of the heat-treated product was 1.0 g / cm ³ , while the density of the remelted product was 2.5 g / cm ^3. The The density of the heat-treated product and the remelted product of Example 2 to which the additive was added was also measured. As a result, the density of the heat-treated product was 1.0 g / cm ³ while the density of the remelted product was 2.4 g. It was / cm ³ . That is, by raising the density by remelting to form a block (block shape), it was possible to obtain a more stable form with low As elution.

1: Inner layer 2: Outer layer

Claims (6)

A roasting step of roasting a copper ore containing arsenic in a non-oxidizing atmosphere and separating it into chalcopyrite and volatiles including arsenic sulfide;
A heat treatment step of heat treating the volatiles obtained in the roasting step under a non-oxidative atmosphere to melt arsenic sulfide in the volatiles;
A grinding step of grinding the volatiles after the heat treatment step;
A re-melting step of heating and re-melting the volatiles after the grinding step in a non-oxidative atmosphere.   The method of treating arsenic according to claim 1, wherein the remelting step includes heating the volatiles at 200 to 250 ° C. The treatment of arsenic according to claim 1 or 2, wherein the remelting step includes heating the volatiles so that the density of the volatiles after remelting is 1.5 to 3.0 g / cm ^3. Method.   The method of treating arsenic according to any one of claims 1 to 3, further comprising adding sulfur in the heat treatment step.   The heat treatment step includes adjusting the content of sulfur so that the mass ratio (S / As mass ratio) of sulfur contained in the volatile matter to arsenic is 1.2 or more. The processing method of the arsenic as described in any one.   The method of treating arsenic according to any one of claims 1 to 5, further comprising adding an anti-aging agent in the heat treatment step.

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