Method for efficiently treating metal ions in acid wastewater prepared by activated carbon method based on sintering process characteristics

Abstract

The application discloses a method for efficiently treating metal ions in acid-making wastewater by activated carbon method based on sintering process characteristics, and steps include synthesis of adsorbent, drying of the adsorbent, removal of heavy metals in acid-making wastewater by the adsorbent, and disposal of waste adsorbent. The synthesis process of the adsorbent is simple, easy to operate, fast in reaction speed, and the waste liquid can be recycled without three waste emissions. The waste heat of the sintering circular cooling machine can be fully utilized through reasonable design to realize efficient utilization of waste heat. The mixed alkali low-alkali precipitation metal-solid adsorption-cyclone separation technology is developed, which can simultaneously realize deep removal of metal ions and inhibition of unorganized ammonia emission. The waste silica adsorbent containing metal ions can be returned to the sintering for high-temperature treatment, thereby recycling silicon resources and simultaneously disposing metal ions.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of based on sintering process feature efficient processing active carbon method of metal ions in method for producing sulphuric acid waste water. BACKGROUND

[0002] Currently, the process of converting sulfur dioxide into sulfuric acid mainly uses solid adsorbents or liquids to adsorb low-concentration sulfur dioxide, and then enriches the sulfur dioxide into high-concentration sulfur dioxide through desorption for the preparation of sulfuric acid. To ensure the quality of sulfuric acid and the stability of the acid-making system, the desorption gas is often washed by washing method to remove impurities, thereby generating a large amount of active carbon method for producing sulphuric acid wastewater. Through previous studies, it is determined that the active carbon method for producing sulphuric acid wastewater has complex composition, especially ammonia nitrogen and metal ions, and the concentration of ammonia nitrogen is extremely high.

[0003] For the acid-making wastewater containing ammonia nitrogen and metal ions, the metal ions need to be removed before the ammonia removal work. However, the removal of hardness and metal ions generally requires a high pH. The ammonia nitrogen in the acid-making wastewater will be converted into free ammonia molecules after the solution is adjusted to alkaline, and finally become ammonia gas precipitated from the liquid phase. The stronger the alkalinity, the easier the ammonia gas escapes, causing the workshop environment to deteriorate.

[0004] If the metal ions can be removed under neutral or weak alkaline conditions, the problems faced by the removal of metal ions under alkaline conditions can be effectively avoided. SUMMARY

[0005] The present application aims to overcome the shortcomings of the prior art and provides a method for efficiently removing metal ions from active carbon method for producing sulphuric acid wastewater based on sintering process characteristics. The process and technical principle of the method are as follows:

[0006] (1) Silicon-based metal ion adsorbent material: KH590 is first prepared into a homogeneous mixture with silicon dioxide, then ammonia water is added to make KH590 hydrolysis and condensation reaction, and the reaction is controlled on the surface of silicon dioxide to modify the silicon dioxide, so as to load methyl, alkyl and mercapto groups. These groups will undergo chelation with metal ions under weak alkaline conditions to achieve good removal of metal ions.

[0007] (2) Sintering low-temperature heat waste gas regulation: according to the analysis and calculation of the temperature characteristics of heat waste gas and the heat demand of catalyst synthesis, the required amount of heat waste gas is determined, and the tee and switch valve on the tail wind box flue gas pipeline are adjusted to obtain the required flue gas for the subsequent process.

[0008] (3) Flocculation weak alkaline precipitation: mixed alkali is used to adjust the acid-making wastewater to weak alkaline, pH≤9; metal cations will react with OH - , CO3 2-or HCO3 - A precipitation reaction occurs, forming insoluble substances. The added adsorbent adsorbs the remaining metal ions, removing metal cations from the acid wastewater. Because the adsorbent is a solid particle, it can be quickly separated by a cyclone reactor.

[0009] (4) Silicon resource recycling: Silica is one of the raw materials for sintering. Waste adsorbents are mainly silicon dioxide, and adding them to the sintering process can 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 achieves the complete harmlessness of metal ions and the 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 the Adsorbent: Silica powder is added to clean water and stirred to form a silica powder dispersion. A silane coupling agent, KH590, is mixed with ethanol and then added to the silica powder dispersion under stirring. After the addition is complete, the pH of the solution is adjusted to 7-9 with aqueous ammonia. The temperature in the reactor is raised to above 80°C using the flue gas from the low-temperature section of the sintering ring cooler for indirect heat exchange with the reactor. The reaction is maintained for 120-240 minutes.

[0013] Step 2) Drying the adsorbent: After the reaction is complete, the solution in the reactor is transferred to a centrifuge for centrifugation. The solution is returned to step 1) for dispersion of fresh silica. The solid is dried using flue gas from the low-temperature section of a sintering ring cooler. The dried solid is then packaged for later use as a dry adsorbent.

[0014] Step 3) Using the adsorbent to remove heavy metals from acid wastewater: slowly adding a mixed alkali to the acid wastewater to adjust the solution pH to 4-12, adding the dried adsorbent to the acid wastewater, and passing the adsorbent through a cyclone reactor with the water flow. The supernatant is the acid wastewater with the 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 batch 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 mixture is 1:8~1:13, and the pH of the mixed alkali solution is adjusted to 8~9.

[0017] Further, the mixing ratio of the silica and water is 1:3~1:5, the mixing ratio of the silane coupling agent KH590 and ethanol is 1:4~1:5, and the mixing ratio of the silicon powder dispersion liquid and the silane coupling agent mixed liquid is 1:9~1:11.

[0018] Further, the flue gas temperature of the sintering ring cooling machine low-temperature section in the step 1) is 100~200℃.

[0019] Further, the mixed alkali in the 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.

[0020] Further, the adsorbent in the step 3) is added into the hydrocyclone reactor with the acid-making wastewater, the residence time is 0.5~1.5h, and the adsorbent addition amount is 1g / L~5g / L.

[0021] Further, the waste adsorbent in the step 4) is added into the sintering layer at the bottom of the sintering trolley of the sintering ring cooling machine.

[0022] Further, the waste adsorbent in the step 4) is added into the sintering layer of the sintering ring cooling machine at a distance of 50~150mm from the bottom of the sintering trolley.

[0023] Further, the waste adsorbent in the step 4) is added into the sintering layer of the sintering ring cooling machine at a distance of 70~125mm from the bottom of the sintering trolley.

[0024] The beneficial effects of the present application are: (1) the adsorbent synthesis process is simple, easy to operate, and fast in reaction speed. The waste liquid can be recycled without three waste emissions. (2) The hot waste gas of the sintering ring cooling machine can be fully utilized. According to the characteristics of the adsorbent synthesis process, reasonable design is carried out to realize efficient utilization of waste heat. (3) Since the acid-making wastewater contains not only metal cations but also a large amount of ammonia nitrogen, if the solution is adjusted to high alkalinity, a large amount of ammonia gas will escape, and if the solution is adjusted to low alkalinity, it is not conducive to the complete precipitation of metal cations. To solve this contradiction, a mixed alkali low-alkali metal ion precipitation-solid adsorption-hydrocyclone separation technology is developed, which can simultaneously realize deep removal of metal ions and inhibit unorganized emission of ammonia. (4) The generated waste silica adsorbent containing metal ions can be returned to the sintering process for high-temperature treatment, which not only recycles silicon resources but also cooperatively disposes metal ions. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is the process flow chart of the present application based on the characteristics of the sintering process for efficiently treating metal ions in the acid-making wastewater by the activated carbon method;

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

[0027] Figure label name: 1-acid waste water inlet, 2-adsorbent inlet, 3-acid waste water outlet, 4-waste adsorbent outlet. DETAILED DESCRIPTION

[0028] The present application will be further described in detail below with examples. A method for efficiently treating metal ions in acid waste water by activated carbon method based on sintering process characteristics, the process flow is shown in Figure 1 The specific implementation includes the following steps:

[0029] Step 1) synthesis of silica modified adsorbent: take silica powder and water in a ratio of 1:5, stir evenly to form a silica powder dispersion, at the same time, take silane coupling agent KH590 and ethanol in a ratio of 1:4, under stirring conditions, add the mixed silica powder dispersion to the silane coupling agent mixture in a ratio of 1:10; after adding, adjust the solution pH to 8 with ammonia; use the low temperature section of the sintering ring cooler to indirectly exchange heat with the reaction kettle, so that the temperature in the reaction kettle rises above 80℃, the low temperature section of the sintering ring cooler is 150℃, and the reaction is maintained for 200 minutes;

[0030] Step 2) drying of the adsorbent: after the reaction is completed, the solution in the reaction kettle is transferred to a centrifuge for centrifugation, and the solution is returned to step 1) for dispersing fresh silica, and the solid is dried using the low temperature section of the sintering ring cooler. After drying, the solid is dried adsorbent, which is ready for use;

[0031] Step 3) adsorbent for removal of heavy metals in acid waste water: slowly add a mixed solution of 15% NaOH and 5% Na2CO3 to the acid waste water, adjust the solution pH to 8.5, then add the dried adsorbent obtained in step 2) to the acid waste water, and pass through the cyclone reactor with the water flow, as shown in Figure 2 The residence time is 1h, and the amount of dried adsorbent added is 3g / L, and the supernatant is the acid waste water from which the metal ions have been removed, and the bottom of the cyclone reactor is the waste adsorbent;

[0032] Step 4) disposal of waste adsorbent: add the waste adsorbent to the sintering ring cooler at a distance of 100mm from the bottom of the sintering trolley.

[0033] The above content is only used to illustrate the technical solutions of the present application, and the simple modifications or equivalent replacements of the technical solutions of the present application made by those skilled in the art do not deviate from the essence and scope of the technical solutions of the present application.

Claims

1. A method for efficiently treating metal ions in activated carbon acid production wastewater based on the characteristics of the sintering process, characterized by: The method comprises the following steps: Step 1) Synthesis of the Adsorbent: Silica powder is added to clean water and stirred to form a silica powder dispersion. A silane coupling agent, KH590, is mixed with ethanol and then added to the silica powder dispersion under stirring. After the addition is complete, the pH of the solution is adjusted to 7-9 with aqueous ammonia. The temperature in the reactor is raised to above 80°C using the flue gas from the low-temperature section of the sintering ring cooler for indirect heat exchange with the reactor. The reaction is maintained for 120-240 minutes. Step 2) Drying the adsorbent: After the reaction is complete, the solution in the reactor is transferred to a centrifuge for centrifugation. The solution is returned to step 1) for dispersion of fresh silica. The solid is dried using flue gas from the low-temperature section of a sintering ring cooler. The dried solid is then packaged for later use as a dry adsorbent. Step 3) Using the adsorbent to remove heavy metals from acid wastewater: slowly adding a mixed alkali to the acid wastewater to adjust the solution pH to 4-12, adding the dried adsorbent to the acid wastewater, and passing the adsorbent through a cyclone reactor with the water flow. The supernatant is the acid wastewater with the 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 batch 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 mixture is 1:8-1:13, and the pH 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, 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 mixture 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, characterized in that: In the step 1), the flue gas temperature in 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, 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, characterized in that: In step 3), the adsorbent and the acid production wastewater are added to the cyclone reactor with a residence time of 0.5 to 1.5 hours and an adsorbent addition amount of 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, 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, characterized in that: The waste adsorbent in step 4) is added to the sintering material layer of the sintering ring cooler 50-150 mm away from the bottom of the sintering trolley.

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

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