JP5840644B2 - Arsenic treatment method - Google Patents

Description

  The present invention relates to a method for treating arsenic, and more particularly to a method for treating arsenic suitable for long-term storage and storage of copper ore containing arsenic.

  In recent years, copper ores collected at copper mines operating all over the world have become the primary sulfide ore, 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 disposed or stored in a stable form.

  For this reason, in the mine smelter, certain restrictions (usually <0.3 mass%) are given to arsenic in the copper concentrate to be purchased. When the limit is exceeded, the mine side generally pays a penalty to the smelter according to the excess amount.

  Therefore, from the mine's point of view, an efficient method for treating sulfide ore containing a large amount of arsenic is an important concern for cost reduction and mine life extension. 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.

  Japanese Patent Application Laid-Open No. 2009-39666 (Patent Document 1) discloses an arsenic treatment method in which an arsenic-containing compound is made into a compact crystalline compound particle form with less moisture and then the obtained crystalline compound is coated with a resin. .

  On the other hand, copper ores containing a large amount of arsenic are generally made into low arsenic grade copper concentrate by removing the cost at the beneficiation stage. However, in recent years, there have also been attempts to treat high arsenic-containing concentrates that remain as high-arsenic grade copper concentrates or have been removed during the beneficiation stage.

  For example, in Japanese Patent Application Laid-Open No. 2012-87400 (Patent Document 2), arsenic copper ore containing relatively high concentration or copper concentrate containing arsenic copper ore is roasted in an inert atmosphere and mainly composed of arsenic sulfide. A method of wet-treating the sinter is divided into a volatile matter to be burned and a sinter mainly composed of chalcopyrite.

JP 2009-39666 A JP 2012-87400 A

  However, in the method described in Patent Document 1, when a compound containing arsenic coated with a resin is stored and stored for a long period of time, the coating is peeled off due to deterioration of the resin or external pressure, and arsenic is removed from the peeled portion. The contained compounds may be eluted.

  The invention described in Patent Document 2 discloses that a sinter is extracted from a copper concentrate containing arsenite or a copper concentrate containing arsenite, and this sinter is wet-treated, but contains arsenic obtained from copper ore. No specific treatment method for volatiles has been described or studied.

  In view of the above problems, the present invention provides an arsenic treatment method capable of treating arsenic contained in copper ore containing arsenic into a stable form that can withstand long-term storage and preservation.

  In order to solve the above-mentioned problems, the present inventor has intensively studied, roasting copper ore containing arsenic, extracting volatiles containing arsenic from the copper ore, and applying a predetermined treatment to the volatiles. The present inventors have found that arsenic elution can be made stable and can be suppressed over a long period of time.

The present invention completed on the basis of the above knowledge is, in one aspect, a roasting step of roasting copper ore containing arsenic in an inert gas atmosphere and separating it into chalcopyrite and volatiles containing arsenic sulfide, A method of treating arsenic comprising adding a sulfur and an anti-aging agent to the volatiles obtained in the roasting step and then heat-treating in an inert gas atmosphere to melt the arsenic sulfide in the volatiles. is there.

  In one embodiment, the arsenic treatment method according to the present invention has a mass ratio (S / As mass ratio) of sulfur to arsenic in the volatile matter of 3 or more with respect to the volatile matter obtained in the roasting step. Including adding sulfur.

In another embodiment, the method for treating arsenic according to the present invention includes adding an anti-aging agent in an amount of 0.2 mol / m ³ or more.

  In still another embodiment of the method for treating arsenic according to the present invention, the anti-aging agent is at least one selected from the group consisting of monophenol, bisphenol, and polyphenol.

  In yet another embodiment, the method for treating arsenic according to the present invention includes heat-treating volatiles at 200 to 600 ° C. in the heat treatment step.

In another aspect of the present invention, copper ore containing arsenic is roasted in an inert gas atmosphere, separated into roasted concentrate and volatiles containing arsenic sulfide, and contained in the volatiles. Adding sulfur as necessary, adding an anti-aging agent to the volatiles, and an anti-aging agent so that the mass ratio of sulfur to arsenic (S / As mass ratio) is 3 or more Is a method for treating arsenic, comprising heat-treating a volatile material to which arsenic is added in an inert gas atmosphere and melting arsenic sulfide in the volatile material.

  ADVANTAGE OF THE INVENTION According to this invention, the processing method of the arsenic which can process the arsenic contained in the copper ore containing arsenic in the stable form which can endure long-term storage and preservation | save can be provided.

It is an example of the microscope picture which shows the property of the volatile matter obtained at the roasting process. Effect of As leaching amount on addition of anti-aging agent to heat-treated products when anti-aging agents A to C are added to volatiles (samples 1 and 3) to which sulfur is added and volatiles (sample 2) to which sulfur is not added and heat-treated It is a graph showing. 2 shows the aging stability of the As elution amount of a conventional arsenic-containing heat-treated product (sample 4) and a heat-treated product containing arsenic (samples 5 to 7) obtained by using the arsenic processing method according to the embodiment of the present invention. It is a graph.

Embodiments for carrying out the present invention will be described below. The processing object in the arsenic processing method according to the embodiment of the present invention is copper ore containing arsenic. Specifically, for example, copper arsenite (Cu ₃ AsS ₄ ), tetrahedral arsenite (Cu ₁₂ As ₄ S ₁₃ ), or copper concentrate in which copper ores containing these arsenic are mixed can be used. In addition to these copper ores, it is a matter of course that the present invention is not limited to the copper ores as long as they are ores containing arsenic and can be processed by the following two-stage treatment.

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

  In this embodiment, it is preferable to pre-dry the copper concentrate at a temperature at which the mineral species and quality do not change. Normally, when copper concentrate is dried with high-temperature air, the temperature of the copper concentrate at the outlet of the dryer is set to approximately 90 ° C., and the moisture content of the copper concentrate is set to 0.5 mass% or less.

  The dried copper concentrate is roasted at 550 ° C. to 700 ° C. for 10 to 60 minutes in an inert gas atmosphere (roasting step). For example, nitrogen gas is used as the inert gas. Control of the treatment temperature and atmosphere in the roasting process is a necessary condition for converting copper concentrate mainly composed of arsenite to arsenic sulfide and chalcopyrite, and the reaction time leaves unreacted arsenite. There is no time needed.

In the roasting step, the formation reaction of arsenic sulfide in the copper concentrate follows the following formula (1) or (2). If the original concentrate contains a lot of pyrite, etc., the S added in the formula (1) is compensated by the generated S by the decomposition of the pyrite in the processing temperature zone as shown in the formula (3). Therefore, 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 process is performed using, for example, a rotary kiln. As shown in the above formulas (1) to (3), an arsenic compound is produced by roasting, and the produced arsenic compound volatilizes at a vapor pressure corresponding to the temperature and is removed from the raw copper concentrate.

  As a result of this roasting treatment, from raw copper concentrate, roasted concentrate (calcined ore) mainly composed of chalcopyrite and Cubanite, volatilization including volatilized and recovered arsenic compound (arsenic sulfide) and elemental sulfur Things are obtained. The ratio of chalcopyrite and cuba ore in the sinter is within the temperature range of 550 ° C to 700 ° C, the amount of copper ores such as chalcopyrite and chalcopyrite included before the reaction, the amount of pyrite included before the reaction, and addition Varies depending on the amount of pyrite produced.

  Since As sulfide and elemental sulfur volatilized in the roasting process are in a gas form, they are cooled, solidified and recovered in an inert atmosphere. FIG. 1 shows an example of a micrograph of recovered volatiles. The recovered volatiles include granular particles having a diameter of about 10 to 15 μm and have a two-layer structure of an inner layer 1 and an outer layer 2 having different As grades.

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

In the heat treatment step carried out after the roasting step, the volatile particles shown in FIG. 1 are further heat-treated in an inert gas atmosphere to melt arsenic sulfide (arsenic sulfide) in the volatile matter, thereby producing volatile matter. In addition to further reducing the arsenic elution property, an anti-aging agent is added in the presence of sulfur to produce a heat-treated product that can be stored stably for a long period of time.

  For example, nitrogen gas is used as the inert gas. The treatment temperature in the heat treatment step 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 dissolved, and the effect of reducing the arsenic elution amount may not be sufficiently obtained. When the processing temperature is higher than 600 ° C., hydrogen sulfide contained as arsenic sulfide in the volatiles is gasified and volatilizes, so that the heat-treated product may not be recovered.

  Although the treatment time of the heat treatment step varies depending on the treatment temperature, in order to completely advance the reaction, it is preferable to carry out the treatment for at least 30 minutes or more, more preferably 50 minutes or more from the aspect of reducing the As elution amount of the heat treatment product. preferable.

  In the heat treatment step, sulfur and an antioxidant are added to the volatiles. Sulfur is added because the volatilization amount of sulfur increases and the arsenic concentration in the volatiles increases as the processing temperature of the heat treatment process increases, and the arsenic elution suppression effect due to the reaction of sulfur with arsenic This is because becomes smaller. For example, when a volatile matter having an S / As mass ratio of 3.0 is treated at 400 ° C., the S content in the volatile matter is volatilized, and the S / As mass ratio is reduced to about 2.4, at 500 ° C. In the case of treatment, the S component volatilizes and the S / As mass ratio may be reduced to about 1.2.

  As the sulfur source to be added, simple sulfur is preferable from the viewpoint of handling. Sulfur may be added before the heat treatment step or may be added during the heat treatment step. In view of the processing efficiency, it is preferable to adjust the concentration in advance before the heat treatment step. The addition of sulfur may not be performed when a large amount of sulfur is previously contained in the copper ore to be treated.

  As the anti-aging agent, an anti-aging agent for rubber can be used. As the rubber anti-aging agent, one or more selected from the group consisting of monophenol, bisphenol and polyphenol are preferably used. When the anti-aging agent reacts with sulfur by a heat treatment described later, deterioration due to oxidation of the heat-treated product containing arsenic obtained after the heat treatment step is suppressed.

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 . The amount added is less than half the amount added to general rubber.

For example, when a monophenol type anti-aging agent is used as an anti-aging agent, it is more preferable to add 0.4 mol / m ³ or more to a volatile material containing arsenic. When using a bisphenol type anti-aging agent as an anti-aging agent, it is more preferable to add 0.9 mol / m ³ or more. When using a polyphenol type anti-aging agent as an anti-aging agent, it is more preferable to add 1.6 mol / m ³ or more. By adding an anti-aging agent to a volatile material containing arsenic and performing heat treatment, it is possible to suppress elution of As from the heat-treated product containing arsenic after the heat treatment over a long period of time.

  In the heat treatment step, volatiles are added by adding sulfur as necessary so that the mass ratio of sulfur to arsenic (S / As mass ratio) in the volatiles is 3 or more, more preferably 4 or more. It is preferable to adjust the concentration of sulfur and arsenic therein. If the S / As mass ratio is, for example, about 2, even if the heat treatment time is increased, the arsenic elution reduction effect over a long period of time may not be sufficiently obtained.

  In addition, there is no restriction | limiting in particular in the upper limit of S / As mass ratio, However, As S / As mass ratio is high, As long-term elution inhibitory effect is acquired by heat processing for a short time. On the other hand, if the amount of sulfur added is increased too much in order to increase the S / As mass ratio, the As elution suppression effect does not change greatly. Rather, since sulfur is excessive with respect to arsenic, excess sulfur content is not increased. Post-processing is required and may increase costs. Therefore, the upper limit of the S / As mass ratio can be about 6.

  The heat-treated product containing arsenic finally obtained by the arsenic treatment method according to the embodiment of the present invention has an arsenic quality of 12 to 15 mol%. The heat-treated product is composed of angular and irregularly shaped granular materials, and there is no bias in the presence of arsenic and sulfur such as volatiles obtained after the roasting process as shown in FIG.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

(Effect of As elution amount due to addition of anti-aging agent)
As the raw material copper concentrate, a high As grade copper concentrate having a Cu grade of 21 mass%, an Fe grade of 23 mass%, an S grade of 38 mass%, and an As grade of 6.8 mass% was used. The main mineral composition characterized using X-ray diffraction (XRD) and electron microanalyzer (EPMA) for this high As grade copper concentrate is 11 mass% of chalcopyrite (CuFeS ₂ ), pyrite (FeS ₂ ). They were 42 mass%, arsenite (Cu ₃ AsS ₄ ) 36 mass%, and gangue components (SiO ₂ etc.) 11 mass%.

  After 100 g of this copper concentrate containing arsenic was pre-dried and then baked at a processing temperature of 650 ° C. in a nitrogen gas atmosphere, as shown in Table 1, the concentrate containing the chalcopyrite containing almost no arsenic (roasted Sinter) and volatiles containing 33% by mass of arsenic and 64% by mass of sulfur.

  When the volatiles obtained in the roasting step were cooled, solidified and recovered, the S / As mass ratio of the volatiles was 2.3. The obtained volatile matter sample 1 was prepared, and volatile samples 2 and 3 prepared by adding simple sulfur to the volatile matter to adjust the S / As mass ratio in the volatile matter to 5.9. An anti-aging agent was added to Samples 1 and 3, and an anti-aging agent was not added to Sample 2.

  When 2,6-di-t-butyl-4-methylphenol was added to sample 1 as a monophenol-based anti-aging agent (anti-aging agent A in FIG. 2) to 0.5 mass% volatiles, and bisphenol When 4-ethyl-6t-notylphenol (also known as 2,2-methylenebis) is added to 2% by mass of volatiles as an anti-aging agent (anti-aging agent B in FIG. 2), a polyphenol anti-aging agent ( In FIG. 2, the As elution amount was evaluated for the case where 2,5-di-t-butylhydroquinone was added to 1% by mass of volatiles as the antioxidant C). For Sample 3, half of Sample 1 was added to the volatile matter for each of the three types of anti-aging agents, and the As elution amount of the heat-treated product was evaluated.

  These samples 1 to 3 were heat-treated in a nitrogen gas atmosphere at a heat treatment time of 30 minutes and a heat treatment temperature of 280 ° C. to obtain heat-treated products. The heat-treated product obtained was confirmed by soil pollutant elution analysis (TCLP) at the US Environmental Protection Agency (EPA). That is, in the elution analysis of the heat-treated product, deionized water, acetic acid or an acetic acid buffer solution is used as the elution solvent for the heat-treated product having a particle size of less than 9.5 mm (0.5 to 5 mm), and the pH is set to 2.88. , Liquid-solid ratio 20, temperature 22.3 ° C, shaking method is 30rpm with rotary shaking, shaking time is 18 hours, solid-liquid separation is eluted as pressure filtration (using 0.6-0.8μm GFF filter) Analysis was carried out. The results are shown in FIG.

  In Sample 2 in which sulfur was not added to the volatiles after the roasting step, the effect of the As elution amount due to the addition of the anti-aging agent was not observed. On the other hand, in Samples 1 and 3 in which sulfur was added to the volatiles after the roasting step, the amount of As elution could be reduced by adding an anti-aging agent compared to the case where no anti-aging agent was added. Sample 3 is an example in which the addition amount of the anti-aging agent is half that of Sample 1, but the As elution amount could be reduced below the environmental standard.

(Stability of As elution amount over time)
Single-body sulfur was added with respect to the volatile matter obtained at the roasting process of Example 1, and S / As mass ratio in a volatile matter was adjusted to 5.9. Sample 4 with no anti-aging agent added to volatiles after adjustment, monophenolic anti-aging agent (2,6-di-t-butyl-4-methylphenol) added to 0.5% by mass of volatiles Sample 5, sample 6 with bisphenol-based anti-aging agent (2,2-methylenebis) added to 2% by mass volatiles, polyphenol-based anti-aging agent (2,5-di-t-butylhydroquinone) with 1% by mass volatilized Samples 7 added to the product were prepared.

  These samples 4 to 7 were heat-treated in a nitrogen gas atmosphere at a heat treatment time of 30 minutes and a heat treatment temperature of 280 ° C. to obtain heat-treated products. The amount of As elution was evaluated on the heat-treated product obtained immediately after the heat treatment and the heat-treated product stored in the air for one month immediately after the heat treatment under the same conditions as in the above elution analysis. The results are shown in FIG.

  In Sample 4 to which no antioxidant was added, the As elution amount could be kept low immediately after the heat treatment, but the As elution amount increased to 40 mg / L after one month. In samples 5 to 7 to which an anti-aging agent was added, the As elution amount could be stably maintained at 5 mg / L or less immediately after heat treatment and after one month without being affected by external effects such as oxidation. It was.

1: Inner layer 2: Outer layer

Claims (6)

A roasting step of roasting copper ore containing arsenic in an inert gas atmosphere and separating it into chalcopyrite and volatiles containing arsenic sulfide;
A heat treatment step of adding sulfur and an anti-aging agent to the volatile matter obtained in the roasting step and then heat-treating in an inert gas atmosphere to melt the arsenic sulfide in the volatile matter. Processing method.   The method includes adding sulfur such that a mass ratio (S / As mass ratio) of sulfur contained in the volatile matter to arsenic is 3 or more with respect to the volatile matter obtained in the roasting step. Item 2. The method for treating arsenic according to Item 1. The method for treating arsenic according to claim 1 or 2, comprising adding 0.2 mol / m ³ or more of the anti-aging agent.   The method for treating arsenic according to any one of claims 1 to 3, wherein the anti-aging agent is at least one selected from the group consisting of monophenol, bisphenol, and polyphenol.   The method for treating arsenic according to any one of claims 1 to 4, wherein in the heat treatment step, the volatile material is heat treated at 200 to 600 ° C. Roasting copper ore containing arsenic in an inert gas atmosphere and separating it into roasted concentrate and volatiles containing arsenic sulfide;
Adding sulfur as necessary so that the mass ratio of sulfur to arsenic contained in the volatiles (S / As mass ratio) is 3 or more;
Adding further anti-aging agents to the volatiles;
A method of treating arsenic, comprising: heat-treating the volatile matter added with the anti-aging agent in an inert gas atmosphere to melt the arsenic sulfide in the volatile matter.