Method for efficiently treating metal ions in activated carbon process acid-making wastewater based on sintering process characteristics

Abstract

The invention discloses a method for efficiently treating metal ions in acid-making wastewater by an activated carbon method based on sintering process characteristics. The method comprises the following steps: synthesizing an adsorbent, drying the adsorbent, removing heavy metals in the acid-making wastewater by using the adsorbent, and absorbing the waste adsorbent. The adsorbent is simple in synthesis process, simple and convenient to operate and high in reaction speed, waste liquid can be recycled, and no three wastes are discharged; hot waste gas of the sintering circular cooler can be fully utilized, reasonable design is carried out, and efficient utilization of waste heat is achieved; according to the invention, a mixed alkali low-alkali metal precipitation-solid adsorption-cyclone separation technology is developed, so that deep removal of metal ions and inhibition of unorganized emission of ammonia can be realized at the same time; and the generated waste silicon dioxide adsorbent containing metal ions can be returned to be sintered for high-temperature treatment, so that the metal ions can be co-treated while silicon resources are recycled.

Description

Technical Field

[0001] The invention relates to a method for efficiently treating metal ions in activated carbon-based acid-making wastewater based on sintering process characteristics. Background Art

[0002] At present, the process of converting sulfur dioxide into sulfuric acid mainly uses solid adsorbent or liquid to adsorb low-concentration sulfur dioxide, and then enriches sulfur dioxide into high-concentration sulfur dioxide through analysis for the preparation of sulfuric acid. In order to ensure the quality of sulfuric acid and the stability of the acid-making system, the washing method is often used to wash and remove impurities from the analytical gas, which produces a large amount of activated carbon acid-making wastewater. Through preliminary research, it was determined that the activated carbon acid-making wastewater has complex components, especially ammonia nitrogen and metals, and the ammonia nitrogen concentration is extremely high.

[0003] For acid wastewater containing ammonia nitrogen and metal ions, it is generally necessary to remove the metal ions before deammonification. However, since the removal of hardness and metal ions generally requires a higher pH, the ammonia nitrogen in the acid wastewater will be converted into free ammonia molecules after the solution is adjusted to alkaline, and finally become ammonia gas and precipitate from the liquid phase. The stronger the alkalinity, the easier it is for ammonia gas to escape, causing the workshop environment to deteriorate.

[0004] If metal ions can be removed under neutral or weakly alkaline conditions, the problems faced in removing metal ions under alkaline conditions can be effectively avoided. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a method for efficiently treating metal ions in activated carbon acid-making wastewater based on the characteristics of the sintering process. The present invention proposes a method for efficiently treating metal ions in activated carbon acid-making wastewater based on the characteristics of the sintering process. The process and technical principles are briefly described as follows:

[0006] (1) Silicon-based metal ion adsorption material: KH590 and silica are first prepared into a homogeneous mixture, and then ammonia water is added to cause KH590 to undergo a hydrolysis and condensation reaction, and the reaction is controlled to react on the surface of silica to achieve the modification of silica, so that it is loaded with methyl, alkyl and mercapto groups. These groups will chelate with metal ions under weak alkaline conditions, achieving good removal of metal ions.

[0007] (2) Sintering low-temperature hot exhaust gas control: According to the temperature characteristics of the hot exhaust gas and the heat demand of catalyst synthesis, the required amount of hot exhaust gas is determined, and the three-way and switching valve on the flue gas duct of the tail wind box are adjusted to obtain the subsequent required flue gas.

[0008] (3) Flocculation weak alkaline precipitation: Use mixed alkali to adjust the acid wastewater to a weak alkaline level of pH ≤ 9; the metal cations will react with OH - 、CO3 2- or HCO3- The precipitation reaction occurs to form insoluble substances. The residual metal ions are adsorbed by the added adsorbent to achieve the removal of metal cations in the acid-making wastewater. Since the adsorbent is a solid particle, it can be quickly separated by the cyclone reactor.

[0009] (4) Silicon resource recycling: Silicon dioxide is one of the raw materials for sintering. Waste adsorbents are mainly silicon dioxide, which can be added to sintering to reduce the use of ingredients. In addition, the metal ions adsorbed in the waste adsorbent can be stabilized during the high temperature process of sintering. This can achieve complete harmlessness of metal ions and recycling of silicon resources.

[0010] In order to achieve the above object, the technical solution adopted by the present invention is:

[0011] A method for efficiently treating metal ions in activated carbon acid production wastewater based on the characteristics of a sintering process comprises the following steps:

[0012] Step 1) Synthesis of adsorbent: Add silica powder to clean water and stir to form a silica powder dispersion, and at the same time, mix silane coupling agent KH590 with ethanol, and add the silica powder dispersion under stirring; after the addition is completed, adjust the pH of the solution to 7-9 with ammonia water; use the flue gas from the low temperature section of the sintering ring cooler to indirectly exchange heat with the reactor, so that the temperature in the reactor rises to above 80°C, and keep the reaction for 120-240 minutes;

[0013] Step 2) Drying of the adsorbent: After the reaction is completed, the solution in the reactor is transferred to a centrifuge for centrifugation, and the solution is returned to step 1) for dispersing fresh silicon dioxide. The solid is dried using flue gas from the low temperature section of a sintering ring cooler. After the solid is dried, it becomes a dry adsorbent, which is packaged for later use;

[0014] Step 3) using the adsorbent to remove heavy metals from acid-making wastewater: slowly adding a mixed alkali to the acid-making wastewater, adjusting the pH of the solution to 4-12, adding the dried adsorbent to the acid-making wastewater, and passing through a cyclone reactor with the water flow, the supernatant is the acid-making wastewater with metal ions removed, and the bottom of the cyclone reactor is the waste adsorbent;

[0015] Step 4) Disposal of the waste adsorbent: the waste adsorbent is added to the sintering ingredients on the sintering trolley of the sintering ring cooler for disposal.

[0016] Furthermore, the mixing ratio of the silicon dioxide and clean water is 1:1-1:10, the mixing ratio of the silane coupling agent KH590 and ethanol is 1:3-1:6, the mixing ratio of the silicon powder dispersion and the silane coupling agent mixed solution is 1:8-1:13, and the pH of the mixed alkali solution is adjusted to 8-9.

[0017] Furthermore, the mixing ratio of the silicon dioxide to clean water is 1:3-1:5, the mixing ratio of the silane coupling agent KH590 to ethanol is 1:4-1:5, and the ratio of the silicon powder dispersion to the silane coupling agent mixed liquid is 1:9-1:11.

[0018] Furthermore, in the step 1), the flue gas temperature of the low temperature section of the sintering ring cooler is 100-200°C.

[0019] Furthermore, the mixed alkali in step 3) mainly comprises OH - and CO3 2- , which is one of the three combinations of sodium hydroxide and sodium carbonate, potassium hydroxide and sodium carbonate, or sodium hydroxide and potassium carbonate.

[0020] Furthermore, in step 3), the adsorbent and the acid-making wastewater are added to a cyclone reactor, the residence time is 0.5 to 1.5 hours, and the amount of adsorbent added is 1 g / L to 5 g / L.

[0021] Furthermore, the waste adsorbent in step 4) is added to the bottom of the sintering material layer on the sintering trolley of the sintering ring cooler.

[0022] Furthermore, the waste adsorbent in step 4) is added into the sintering material layer of the sintering ring cooler at a distance of 50 to 150 mm from the bottom of the sintering trolley.

[0023] Furthermore, the waste adsorbent in step 4) is added into the sintering material layer of the sintering ring cooler at a distance of 70 to 125 mm from the bottom of the sintering trolley.

[0024] The beneficial effects of the present invention are: (1) The adsorbent synthesis process is simple, easy to operate, and has a fast reaction speed. The waste liquid can be recycled and no three wastes are discharged. (2) The hot exhaust gas of the sintering ring cooler can be fully utilized. According to the characteristics of the adsorbent synthesis process, a reasonable design is carried out to achieve efficient utilization of waste heat. (3) Since the acid-making wastewater contains a large amount of ammonia nitrogen in addition to metal cations, if the solution is adjusted to a high alkalinity, a large amount of ammonia will escape. If the solution is adjusted to a lower alkalinity, it will be unfavorable for the complete precipitation of metal cations. In order to resolve this contradiction, a mixed alkali low-alkali precipitation metal-solid adsorption-cyclone separation technology has been developed, which can simultaneously achieve deep removal of metal ions and inhibit the unorganized emission of ammonia. (4) The waste silica adsorbent containing metal ions can be returned to the sintering for high-temperature treatment, which can recover silicon resources while co-disposing of metal ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a process flow chart of the present invention for efficiently treating metal ions in activated carbon acid production wastewater based on the characteristics of the sintering process;

[0026] Figure 2It is a schematic diagram of a cyclone reactor of the present invention;

[0027] The numbers in the figure are: 1-acid wastewater inlet, 2-adsorbent inlet, 3-acid wastewater outlet, 4-waste adsorbent outlet. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with the embodiments. A method for efficiently treating metal ions in activated carbon acid production wastewater based on the characteristics of the sintering process, the process flow is as follows: Figure 1 As shown, the specific implementation includes the following steps:

[0029] Step 1) Synthesis of silica modified adsorbent: silica powder is mixed with clean water at a ratio of 1:5, and stirred evenly to form a silica powder dispersion. At the same time, silane coupling agent KH590 is mixed with ethanol at a ratio of 1:4, and the mixed silica powder dispersion is added under stirring at a ratio of 1:10 between the silica powder dispersion and the silane coupling agent mixture. After the addition, ammonia water is used to adjust the pH of the solution to 8. The low-temperature section flue gas of the sintering ring cooler is used for indirect heat exchange with the reactor, so that the temperature in the reactor is raised to above 80°C, the low-temperature section flue gas temperature is 150°C, and the reaction is maintained for 200 minutes.

[0030] Step 2) Drying of the adsorbent: After the reaction is completed, the solution in the reactor is transferred to a centrifuge for centrifugation, and the solution is returned to step 1) for dispersion of fresh silica, and the solid is dried using the flue gas from the low temperature section of the sintering ring cooler. The solid is dried to obtain a dry adsorbent, which is packaged for later use;

[0031] Step 3) Adsorbent is used to remove heavy metals from acid wastewater: a mixed solution of 15% NaOH and 5% Na2CO3 is slowly added to the acid wastewater, the pH of the solution is adjusted to 8.5, and then the dry adsorbent obtained in step 2) is added to the acid wastewater, and the adsorbent is passed through a cyclone reactor with the water flow, such as Figure 2 As shown, the residence time is 1 h, the amount of dry adsorbent added is 3 g / L, the supernatant is the acid-making wastewater with metal ions removed, and the bottom of the cyclone reactor is the waste adsorbent.

[0032] Step 4) Disposal of waste adsorbent: Add the waste adsorbent into the sintering batching layer of the sintering ring cooler 100 mm away from the bottom of the sintering trolley.

[0033] The above contents are only used to illustrate the technical solution of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention made by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for efficiently treating metal ions in activated carbon acid production wastewater based on the characteristics of the sintering process, characterized in that: The method comprises the following steps: Step 1) Synthesis of adsorbent: Add silica powder to clean water and stir to form a silica powder dispersion, and at the same time, mix silane coupling agent KH590 with ethanol, and add the silica powder dispersion under stirring; after the addition is completed, adjust the pH of the solution to 7-9 with ammonia water; use the flue gas from the low temperature section of the sintering ring cooler to indirectly exchange heat with the reactor, so that the temperature in the reactor rises to above 80°C, and keep the reaction for 120-240 minutes; Step 2) Drying of the adsorbent: After the reaction is completed, the solution in the reactor is transferred to a centrifuge for centrifugation, and the solution is returned to step 1) for dispersing fresh silicon dioxide. The solid is dried using flue gas from the low temperature section of a sintering ring cooler. After the solid is dried, it becomes a dry adsorbent, which is packaged for later use; Step 3) using the adsorbent to remove heavy metals from acid-making wastewater: slowly adding a mixed alkali to the acid-making wastewater, adjusting the pH of the solution to 4-12, adding the dried adsorbent to the acid-making wastewater, and passing through a cyclone reactor with the water flow, the supernatant is the acid-making wastewater with metal ions removed, and the bottom of the cyclone reactor is the waste adsorbent; Step 4) Disposal of the waste adsorbent: the waste adsorbent is added to the sintering ingredients on the sintering trolley of the sintering ring cooler for disposal.

2. The method for efficiently treating metal ions in activated carbon acid production wastewater based on the characteristics of the sintering process according to claim 1 is characterized in that: The mixing ratio of the silicon dioxide and clean water is 1:1-1:10, the mixing ratio of the silane coupling agent KH590 and ethanol is 1:3-1:6, the mixing ratio of the silicon powder dispersion and the silane coupling agent mixed solution is 1:8-1:13, and the pH value of the mixed alkali solution is adjusted to 8-9.

3. The method for efficiently treating metal ions in activated carbon acid production wastewater based on the characteristics of the sintering process according to claim 2 is characterized in that: The mixing ratio of the silicon dioxide to clean water is 1:3-1:5, the mixing ratio of the silane coupling agent KH590 to ethanol is 1:4-1:5, and the ratio of the silicon powder dispersion to the silane coupling agent mixed liquid is 1:9-1:

11.

4. The method for efficiently treating metal ions in activated carbon acid production wastewater based on the characteristics of the sintering process according to claim 1 is characterized in that: In the step 1), the flue gas temperature of the low temperature section of the sintering ring cooler is 100-200°C.

5. The method for efficiently treating metal ions in activated carbon acid production wastewater based on the characteristics of the sintering process according to claim 1 is characterized in that: The mixed alkali in step 3) mainly includes OH - and CO3 2- , which is one of the three combinations of sodium hydroxide and sodium carbonate, potassium hydroxide and sodium carbonate, or sodium hydroxide and potassium carbonate.

6. The method for efficiently treating metal ions in activated carbon acid production wastewater based on the characteristics of the sintering process according to claim 1 is characterized in that: In the step 3), the adsorbent and the acid-making wastewater are added to the cyclone reactor, the residence time is 0.5 to 1.5 hours, and the amount of adsorbent added is 1 g / L to 5 g / L.

7. The method for efficiently treating metal ions in activated carbon acid production wastewater based on the characteristics of the sintering process according to claim 1 is characterized in that: The waste adsorbent in step 4) is added to the bottom of the sintering material layer on the sintering trolley of the sintering ring cooler.

8. The method for efficiently treating metal ions in activated carbon acid production wastewater based on the characteristics of the sintering process according to claim 7 is characterized in that: The waste adsorbent in step 4) is added into the sintering material layer of the sintering ring cooler at a distance of 50 to 150 mm from the bottom of the sintering trolley.

9. The method for efficiently treating metal ions in activated carbon acid production wastewater based on the sintering process characteristics according to claim 8, characterized in that: The waste adsorbent in step 4) is added into the sintering batching layer of the sintering ring cooler at a distance of 70 to 125 mm from the bottom of the sintering trolley.

Images