Method for treating high-arsenic acid wastewater by external field reinforced copper slag and recovering iron element of high-arsenic acid wastewater

Abstract

The invention provides a method for treating high-arsenic acid wastewater and recycling iron elements through external field strengthened copper slag, and relates to the technical field of heavy metal pollution treatment. The method comprises the following steps: adding copper slag powder into a sulfuric acid solution, carrying out a Fe < 2 + > / Fe < 3 + > dissolution reaction under the action of ultrasonic waves, then adding a catalyst, an oxidant and high-arsenic acidic wastewater into the solution, and carrying out an arsenic precipitation reaction under the action of ultraviolet irradiation and ultrasonic waves to obtain an arsenic-containing precipitate and a filtrate A; introducing oxygen into the filtrate A, and adding ammonia water for hydrolysis reaction to obtain a precipitate and filtrate B; and adding lime milk into the filtrate B, and carrying out deep purification reaction to obtain precipitated sludge and clear water. The arsenic precipitation and iron extraction technology of the external field reinforced copper slag is introduced, operation is easy, the reaction period is short, the arsenic-containing precipitation slag amount is small and stable, the arsenic removal effect is remarkable, the purity of the obtained iron oxyhydroxide precipitate is larger than or equal to 90%, metallurgical solid waste treatment with waste is achieved to the maximum extent, meanwhile, resource utilization of valuable components of the metallurgical solid waste is achieved, and economic benefits are remarkable.

Description

Technical Field

[0001] The invention relates to the technical field of heavy metal pollution control, in particular to a method for treating high-arsenic acid wastewater with externally enhanced copper slag and recovering iron elements thereof. Background Art

[0002] Copper slag is a large solid waste produced by copper smelters. It contains rich valuable resources. However, the traditional treatment methods are mostly direct storage or landfill, which not only wastes a lot of metal resources, but also may cause long-term pollution to the environment, bringing huge pressure to enterprises. In recent years, with the development of technology and the enhancement of environmental protection awareness, the resource utilization of copper smelting slag has gradually become a research hotspot. The chemical composition of copper slag is mainly Fe 2 O 3 、SiO 2 、CaO、MgO、Al 2 O 3 The copper slag contains a small amount of Zn, Cu and Ni, among which the valuable iron content reaches the grade of lean iron ore mining, which is a valuable iron resource. However, the iron element in copper slag is mainly olivine (FeSiO 4 About 90%), a small part of which is iron oxide (FeO and Fe 3 O 4 ) exists in the form of copper slag, and it is difficult to effectively recover the iron in it using traditional mineral processing methods. At present, the recovery of iron in copper slag is mainly carried out by modifying copper slag to enrich magnetite through oxidation or reduction roasting-magnetic separation process. This process can obtain magnetite concentrate with high recovery rate and grade, but it consumes a lot of energy, and after melting, it will stick to the crucible and is not easy to separate, resulting in a reduced recovery rate. Therefore, it is urgent to find a method for efficiently recycling iron in copper slag.

[0003] High arsenic acid wastewater is an important pollution source in the non-ferrous heavy metal smelting industry. It has the characteristics of complex composition, high acidity and strong toxicity. Its safe disposal has become an important problem that needs to be solved urgently in the non-ferrous heavy metal smelting industry. The traditional lime iron salt method and sulfidation method have simple operation processes, but the arsenic-containing precipitates produced have high toxicity leaching, poor stability and large slag volume, which pollutes the ecological environment. It is worth noting that copper slag contains rich iron sources and a small amount of alkaline oxides, which is expected to become an adsorbent and precipitant for arsenic ions and heavy metal ions in high arsenic acid wastewater.

[0004] A series of technologies for treating arsenic acid wastewater with copper slag, such as Chinese patent publication No. CN111003775B (a method for treating arsenic in waste acid by using copper slag in combination with carbide slag), CN110759394B (a method for treating arsenic in waste acid from non-ferrous smelting using biochar and copper slag), CN106745416B (an application of high-temperature molten copper slag to treat arsenic and fluorine in waste acid and its application method), CN106586976B (a method for concentrating waste acid by quenching hot copper slag with hot air), CN111069228A (a method for stabilizing scorodite by encapsulating copper slag with gel), and CN110669 923A (a method for removing arsenic by adsorption of limonite and copper slag), CN110171886A (a method for treating arsenic-containing waste acid by cascading copper slag), CN109534476A (a method for treating arsenic in non-ferrous smelting waste acid by copper slag) and CN109621276A (a method for treating arsenic in non-ferrous smelting waste acid by iron-rich copper slag), etc., have many shortcomings in actual industrial applications, such as long reaction cycle, need to be carried out at a set temperature (high energy consumption, difficult to operate), residual iron in the solution after arsenic precipitation reaction directly enters the tailings, and the long reaction cycle seriously limits the batch treatment of arsenic-containing acidic wastewater. For this reason, further optimization and improvement are needed to address the above problems.

[0005] In addition, Chinese patent publication number CN117482891A discloses a method for deep purification of smelting waste slag solution, wherein the zinc leaching waste slag is pre-treated by microwave vacuum sintering and then added to an arsenic-containing solution for ultrasonic enhanced reaction for 0.5 to 5 hours, and finally a purified solution and arsenic-containing solid slag are obtained. In this invention, the microwave vacuum sintering pre-treatment of zinc leaching waste slag before arsenic removal is expensive and energy-intensive. In addition, the ultrasonic cycle in the reaction system is long, which is not conducive to the economical and efficient disposal of bulk solid waste / liquid.

[0006] In summary, the existing copper slag iron extraction process technology has the disadvantages of high energy consumption and low efficiency, while the high arsenic acid wastewater treatment process technology has the disadvantages of complex operation, long reaction cycle, high operating cost and unstable arsenic-containing sludge. Summary of the invention

[0007] In order to solve the above-mentioned technical problems existing in the prior art, an embodiment of the present invention provides a method for treating high-arsenic acid wastewater and recovering its iron elements by using external field-enhanced copper slag. This method adopts external field-enhanced copper slag for the first time to harmlessly treat high-arsenic acid wastewater and recycle the iron elements in the copper slag, wherein superconducting enhancement is beneficial to shortening the reaction cycle, and the arsenic precipitation reaction rate of the enhanced system, and the synergistic effect of ultraviolet rays, catalysts and oxidants effectively promotes the conversion of arsenite into arsenate in high-arsenic acid wastewater, and reduces the toxicity of arsenic ions in the environment. In short, the present invention has the advantages of simple operation, short reaction cycle, small and stable amount of arsenic-containing precipitated slag, significant arsenic removal effect, and high purity of oxyhydroxide iron precipitate.

[0008] The technical solution is as follows:

[0009] A method for treating high-arsenic acid wastewater and recovering iron elements by using external field enhanced copper slag, the method comprising:

[0010] S1, crushing and grinding the copper slag to obtain copper slag powder;

[0011] S2, mixing the copper slag powder obtained in step S1 with a sulfuric acid solution, and performing Fe 2+ / Fe 3+ Dissolution reaction to obtain a solid-liquid mixture;

[0012] S3, adding a catalyst, an oxidant and high-arsenic acid wastewater to the solid-liquid mixture obtained in step S2, and controlling the pH of the solution to be 0.5-3, and performing an arsenic precipitation reaction under ultraviolet irradiation and ultrasonic action to obtain an arsenic-containing precipitate and a filtrate A;

[0013] S4, introducing oxygen into the filtrate A obtained in step S3, and adding ammonia water to control the pH of the solution to 4-8, performing an iron ion hydrolysis reaction to obtain an iron oxyhydroxide precipitate and a filtrate B;

[0014] S5. Add lime milk solution to the filtrate B obtained in step S4, and control the solution pH to be ≥9 to perform deep purification reaction of residual heavy metal ions, sulfate ions and silicate ions to obtain precipitated sludge such as calcium silicate and calcium sulfate and clear water.

[0015] Preferably, in step S1, the Fe content of the copper slag is ≥36%, and the particle size of the copper slag powder is ≤0.38 μm.

[0016] Specifically, the copper slag is crushed and ground to less than 38 μm, which is beneficial to increase the reaction contact area.

[0017] Preferably, in step S2, the concentration of sulfuric acid is ≥65%, and the solid-liquid ratio of copper slag powder to sulfuric acid is 1: (1.5-2) t / m 3 .

[0018] Preferably, in step S2, the ultrasonic power is 50-1000 W, the ultrasonic time is 15-20 min, and the stirring speed is 200-280 r / min.

[0019] Preferably, in step S3, the catalyst is one of zero-valent iron, titanium dioxide or zirconium oxide; the oxidant is one of ozone, hydrogen peroxide or sodium persulfate; the arsenic ion concentration in the high-arsenic acid wastewater is greater than 0.2 g / L, and the volume of the high-arsenic acid wastewater added is 8 to 15 times that of the solid-liquid mixture.

[0020] Preferably, in step S3, the pH value of the solution is controlled by adding NaOH or KOH; the ultrasonic power during the reaction is 50-1300W, and the ultraviolet intensity is 50-400mV / cm 3 The ultrasonic and light irradiation times are both 25 to 60 min, and the stirring speed is 200 to 280 r / min.

[0021] Preferably, the oxygen flow rate in step S4 is ≥100m 3 / h, the reaction time is 5 to 20 min; the amount of ammonia water is determined by the pH value of the solution; the purity of the obtained ferric oxyhydroxide precipitate is ≥90%.

[0022] Preferably, in step S5, the concentration of the lime milk solution is 20-50%, the reaction time is 5-20 min, and the stirring speed is 200-280 r / min; the amount of the lime milk solution is determined by the pH value of the solution; and the clean water finally obtained meets the comprehensive discharge standard for industrial wastewater.

[0023] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0024] (1) The present invention uses ultrasound to enhance the dissolution of copper slag and release Fe 2+ and Fe 3+ ions, maximizing the leaching of iron in copper slag; in addition, ultrasound can reduce the energy barrier that needs to be overcome by the total reaction or partial reaction involved in the arsenic precipitation reaction process, thereby accelerating the precipitation rate of ferric arsenate and shortening the reaction cycle.

[0025] (2) Ultraviolet light and catalysts are beneficial to promote the 2+ The Fenton reaction with the oxidant accelerates the reaction of arsenite and Fe in the polluted acid. 2+ ion oxidation rate, thereby promoting Fe 3+ It reacts with arsenate to form arsenic-containing precipitate, shortening the reaction time.

[0026] (3) The present invention uses copper slag to treat high-arsenic acid wastewater from the non-ferrous smelting industry, thereby improving the resource utilization rate of copper slag, which is in line with the concept of "treating waste with waste" advocated by the country. At the same time, the toxic leaching concentration of arsenic ions in the arsenic-containing precipitate produced is lower than the general solid waste storage standard, which is safe and friendly to the environment.

[0027] (4) The harmless treatment of waste acid in the present invention realizes efficient recovery and utilization of iron in copper slag without generating pollution; in addition, the precipitated sludge can be reused as building materials, cement ingredients, etc., thus achieving multiple goals at one stroke. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 It is a process flow chart of the present invention;

[0030] Figure 2 This is a TEM image of the arsenic-containing precipitate in Example 3 of the present invention. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0032] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "example" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "example" is intended to present the concept in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or it can be either of the two.

[0033] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0034] The chemical composition of the copper slag used in the following examples of the present invention is shown in Table 1.

[0035] Table 1

[0036] element TFe <![CDATA[SiO 2 ]]> <![CDATA[Al 2 THE 3 ]]> <![CDATA[Na 2 The]]> CuO <![CDATA[SO 3 ]]> CaO MgO <![CDATA[K 2 The]]> Others Content (wt.%) 39.34 27.32 3.74 0.46 0.7 2.28 1.95 2.52 0.68 4.1

[0037] Example 1

[0038] Methods for treating high arsenic acid wastewater with copper slag and recovering iron from it, such as Figure 1 As shown, the specific steps include:

[0039] (1) crushing and grinding the copper slag to less than 30 μm to obtain copper slag powder;

[0040] (2) Copper slag powder and 65% sulfuric acid solution were mixed at a solid-liquid ratio of 1:2 t / m 3 Mixing, Fe was carried out under the conditions of ultrasonic power of 50W, ultrasonic time of 20min, and stirring speed of 280r / min. 2+ / Fe 3+ Dissolution reaction to obtain a solid-liquid mixture;

[0041] (3) Nano-zero-valent iron, hydrogen peroxide, and high-arsenic acid wastewater (arsenic ion concentration of 0.3 g / L) were added to the solid-liquid mixture, and the pH of the solution was controlled to 0.5 by NaOH. The ultrasonic power was 50 W and the ultraviolet intensity was 50 mV / cm 3 , the reaction time is 60min, and the stirring speed is 280r / min. Arsenic precipitation reaction is carried out under the conditions of obtaining an arsenic-containing precipitate and a filtrate A, wherein the arsenic ion toxicity leaching concentration in the arsenic-containing precipitate is 0.23mg / L, which is lower than the general solid waste storage standard; wherein the volume of high arsenic acid wastewater added is 8 times that of the solid-liquid mixture;

[0042] (4) The flow rate of 100 m / s into filtrate A 3 / h of oxygen, and adding ammonia water to control the solution pH to 4, and performing iron ion hydrolysis reaction for 5 minutes to obtain iron oxyhydroxide precipitate and filtrate B, wherein the iron oxyhydroxide precipitate has a purity of 90%;

[0043] (5) A 20% lime milk solution was added to the filtrate B, and the pH value of the solution was controlled to 9 by the lime milk solution. The residual heavy metal ions, sulfate ions and silicate ions were deeply purified for 15 minutes at a stirring speed of 200 r / min to obtain precipitated sludge such as calcium silicate and calcium sulfate and clear water, wherein the arsenic ion concentration in the clear water was 0.01 mg / L.

[0044] Example 2

[0045] Methods for treating high arsenic acid wastewater with copper slag and recovering iron from it, such as Figure 1 As shown, the specific steps include:

[0046] (1) crushing and grinding the copper slag to less than 38 μm to obtain copper slag powder;

[0047] (2) Copper slag powder and 68% sulfuric acid solution were mixed at a solid-liquid ratio of 1:1.5 t / m 3 Mixing, Fe was carried out under the conditions of ultrasonic power of 400 W, ultrasonic time of 16 min, and stirring speed of 200 r / min. 2+ / Fe 3+ Dissolution reaction to obtain a solid-liquid mixture;

[0048] (3) Titanium dioxide, ozone and high arsenic acid wastewater (arsenic ion concentration of 10 g / L) were added to the solid-liquid mixture, and the solution pH was controlled to 2.0 by KOH. The ultrasonic power was 800 W and the ultraviolet intensity was 200 mV / cm 3, the reaction time is 20min, and the stirring speed is 200r / min. Arsenic precipitation reaction is carried out to obtain arsenic-containing precipitate and filtrate A, wherein the arsenic ion toxicity leaching concentration in the arsenic-containing precipitate is 0.17mg / L, which is lower than the general solid waste storage standard; wherein the volume of high arsenic acid wastewater added is 9 times that of the solid-liquid mixture;

[0049] (4) The flow rate of filtrate A is 130m 3 / h of oxygen, and adding ammonia water to control the solution pH to 6, and performing iron ion hydrolysis reaction for 15 minutes to obtain iron oxyhydroxide precipitate and filtrate B, wherein the iron oxyhydroxide precipitate has a purity of 95%;

[0050] (5) A 40% lime milk solution is added to the filtrate B obtained in step S4, and the pH value of the solution is controlled to 12 by the lime milk solution, and a deep purification reaction of residual heavy metal ions, sulfate ions and silicate ions is carried out for 5 minutes. The stirring speed during the reaction is 260 r / min, and precipitated sludge such as calcium silicate and calcium sulfate and clear water are obtained, wherein the arsenic ion concentration in the clear water is 0.05 mg / L.

[0051] Example 3

[0052] Methods for treating high arsenic acid wastewater with copper slag and recovering iron from it, such as Figure 1 As shown, follow the steps below:

[0053] (1) crushing and grinding the copper slag to less than 38 μm to obtain copper slag powder;

[0054] (2) The copper slag obtained in step S1 and a sulfuric acid solution with a concentration of 75% were mixed at a solid-liquid ratio of 1:1.2 t / m 3 The Fe 2+ / Fe 3+ Dissolution reaction to obtain a solid-liquid mixture;

[0055] (3) zirconium oxide, sodium persulfate and high arsenic acid wastewater (arsenic ion concentration of 15 g / L) were added to the solid-liquid mixture obtained in step S2, and the pH of the solution was controlled to 3 by NaOH. The ultrasonic power was 1300 W and the ultraviolet intensity was 400 mV / cm 3 , the reaction time is 45min, and the stirring speed is 260r / min. Arsenic precipitation reaction is carried out under the conditions of obtaining arsenic-containing precipitate and filtrate A, wherein the arsenic ion toxicity leaching concentration in the arsenic-containing precipitate is 0.31mg / L, which is lower than the general solid waste storage standard; wherein the volume of high arsenic acid wastewater added is 15 times that of the solid-liquid mixture;

[0056] (4) Air was introduced into the filtrate A obtained in step S3 at a flow rate of 180 m / s. 3 / h to obtain oxygen, and add ammonia water to control the solution pH to 8, and carry out iron ion hydrolysis reaction for 20 minutes to obtain iron oxyhydroxide precipitate and filtrate B, wherein the purity of the iron oxyhydroxide precipitate is 93%;

[0057] (5) A 50% lime milk solution is added to the filtrate B obtained in step S4, and the pH of the solution is controlled to 13 by the lime milk solution to perform a deep purification reaction of residual heavy metal ions, sulfate ions and silicate ions for 20 minutes. The stirring speed during the reaction is 280 r / min, and precipitated sludge such as calcium silicate and calcium sulfate and clear water are obtained, wherein the arsenic ion concentration in the clear water is 0.04 mg / L.

[0058] TEM image of arsenic-containing precipitate Figure 2 As shown. Figure 2 It can be seen that the arsenic-containing precipitate has an obviously irregular shape. The EDS results of the arsenic-containing precipitate show that the arsenic-containing precipitate is mainly ferric arsenate, indicating that the arsenate in the high-arsenic wastewater reacts with Fe 3+ The reaction produced a ferric arsenate precipitate.

[0059] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for treating high-arsenic acid wastewater and recovering iron from it by using external field-enhanced copper slag, characterized in that: The method comprises: S1, crushing and grinding the copper slag to obtain copper slag powder; S2, mixing the copper slag powder obtained in step S1 with a sulfuric acid solution, and performing Fe 2+ / Fe 3+ Dissolution reaction to obtain a solid-liquid mixture; S3, adding a catalyst, an oxidant and high-arsenic acid wastewater to the solid-liquid mixture obtained in step S2, and controlling the pH of the solution to be 0.5-3, and performing an arsenic precipitation reaction under ultraviolet irradiation and ultrasonic action to obtain an arsenic-containing precipitate and a filtrate A; S4, introducing oxygen into the filtrate A obtained in step S3, and adding ammonia water to control the pH of the solution to 4-8, performing an iron ion hydrolysis reaction to obtain an iron oxyhydroxide precipitate and a filtrate B; S5. Add lime milk solution to the filtrate B obtained in step S4, and control the solution pH to be ≥9 to perform deep purification reaction of residual heavy metal ions, sulfate ions and silicate ions to obtain precipitated sludge and clean water.

2. The method for treating high-arsenic acid wastewater and recovering iron from the copper slag by external field strengthening according to claim 1 is characterized in that: In the step S1, the Fe content of the copper slag is ≥36%, and the particle size of the copper slag powder is ≤0.38 μm.

3. The method for treating high-arsenic acid wastewater and recovering iron from the copper slag by external field strengthening according to claim 1 is characterized in that: In step S2, the concentration of sulfuric acid is ≥65%, and the solid-liquid ratio of copper slag powder to sulfuric acid is 1: (1.5-2) t / m 3 .

4. The method for treating high-arsenic acid wastewater and recovering iron from the copper slag by external field strengthening according to claim 1 is characterized in that: In step S2, the ultrasonic power is 50-1000W, the ultrasonic time is 15-20min, and the stirring speed is 200-280r / min.

5. The method for treating high-arsenic acid wastewater and recovering iron from the copper slag by external field strengthening according to claim 1 is characterized in that: In step S3, the catalyst is one of zero-valent iron, titanium dioxide or zirconium oxide; the oxidant is one of ozone, hydrogen peroxide or sodium persulfate; the arsenic ion concentration in the high-arsenic acid wastewater is greater than 0.2 g / L, and the volume of the high-arsenic acid wastewater added is 8 to 15 times that of the solid-liquid mixture.

6. The method for treating high-arsenic acid wastewater and recovering iron from the copper slag by external field strengthening according to claim 1 is characterized in that: In step S3, the pH value of the solution is controlled by adding NaOH or KOH; the ultrasonic power during the reaction is 50-1300W, and the ultraviolet intensity is 50-400mV / cm 3 The ultrasonic and light irradiation times are both 25 to 60 min, and the stirring speed is 200 to 280 r / min.

7. The method for treating high-arsenic acid wastewater and recovering iron from the wastewater by using external field enhanced copper slag according to claim 1, characterized in that: The oxygen flow rate in step S4 is ≥100m 3 / h, reaction time is 5 to 20 minutes.

8. The method for treating high-arsenic acid wastewater and recovering iron from the wastewater by using external field enhanced copper slag according to claim 1, characterized in that: In step S5, the concentration of the lime milk solution is 20-50%, the reaction time is 5-20 minutes, and the stirring speed is 200-280 r / min.

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