Segmented neutralization process for comprehensively utilizing calcium carbonate powder and calcium oxide

Abstract

The invention discloses a sectional neutralization process for comprehensively utilizing calcium carbonate powder and calcium oxide, belongs to the technical field of wastewater treatment, and aims to solve the problems that a large amount of lime is consumed in the industrial wastewater treatment process of most enterprises and excessive lime is easy to put for thorough treatment. Three neutralization pools are respectively adopted in the neutralization stage of calcium carbonate and calcium oxide for segmented neutralization, the segmented neutralization reaction increases the reaction time, the pH values in two adjacent neutralization pools are set to be gradient, and the change amplitude of the pH values in the two adjacent neutralization pools is relatively small, so that the pH values in the two adjacent neutralization pools are relatively small. The addition amount of calcium carbonate and calcium oxide can be more accurately controlled, so that calcium carbonate and wastewater are buffered by the three-stage neutralization tank and can be fully mixed, and the reaction efficiency and the utilization rate of calcium carbonate and calcium oxide are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a staged neutralization process for comprehensively utilizing calcium carbonate powder and calcium oxide. Background Art

[0002] At present, the treatment of industrial wastewater at home and abroad mainly includes three aspects: one is the treatment of industrial wastewater, which is to remove pollutants in industrial wastewater through physical, biological and other means, so that the water body of the sewage can meet the water quality requirements for discharge or reuse; the second is sewage recycling, which means that after proper treatment, the sewage reaches a certain water quality standard, meets certain usage requirements, and can be used beneficially, which belongs to the deep treatment of sewage; the third is sludge treatment, which refers to the landfill and other treatment of the sludge generated after sewage treatment.

[0003] The wastewater targeted in this application is mainly wastewater from the titanium dioxide production field, and the main components of the wastewater are sulfuric acid and ferrous sulfate. The mainstream treatment of this wastewater at home and abroad is chemical precipitation. During the treatment, lime is added for precipitation. While neutralizing the acid in the industrial wastewater, a large amount of heavy metals present in the industrial wastewater can be removed. At present, most companies consume a large amount of lime in the industrial wastewater treatment process, and in order to thoroughly treat the wastewater, it is easy to cause excessive lime addition. In order to save costs, companies need to find a wastewater treatment method that can save more costs. Summary of the invention

[0004] In view of the problems in the prior art, the present invention provides a staged neutralization process for comprehensively utilizing calcium carbonate powder and calcium oxide. Three neutralization tanks are respectively used for staged neutralization in the stages of neutralization of calcium carbonate and calcium oxide. The staged neutralization reaction increases the reaction time. Since the pH values ​​in two adjacent neutralization tanks are set to be gradient, and the pH value variation range in the two adjacent neutralization tanks is set to be small, the addition amount of calcium carbonate and calcium oxide can be more accurately controlled. Therefore, the three-stage neutralization tank allows calcium carbonate and wastewater to form a buffer, which can be fully mixed, thereby improving the reaction efficiency and the utilization rate of calcium carbonate and calcium oxide.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A staged neutralization process for comprehensive utilization of calcium carbonate powder and calcium oxide, characterized in that it comprises the following steps:

[0007] Step 1: The wastewater is sequentially passed into the primary neutralization tank, the secondary neutralization tank, and the tertiary neutralization tank, and calcium carbonate is used for neutralization. The pH value in each neutralization tank is controlled respectively, so that the pH value of the wastewater discharged from the tertiary neutralization tank is 4.0-4.5;

[0008] Step 2: Discharge the tertiary wastewater into the fourth, fifth and sixth neutralization tanks in sequence, use calcium oxide for neutralization, and control the pH value in each neutralization tank respectively, so that the pH value of the wastewater discharged from the sixth neutralization tank is 8.0-9.0.

[0009] Preferably, the pH value of the primary neutralization tank in step 1 is controlled to be 3.0-3.5.

[0010] Preferably, the pH value of the secondary neutralization tank in step 1 is controlled to be 3.5-4.0.

[0011] Preferably, the pH value of the four-stage neutralization tank in step 2 is controlled to be 5.0-6.0.

[0012] Preferably, the pH value of the five-stage neutralization tank in step 2 is controlled to be 6.0-7.5.

[0013] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0014] 1. As a more environmentally friendly neutralizer, calcium carbonate can reduce the burden on the environment and meet the current environmental protection requirements and trends;

[0015] 2. In the traditional process, the amount of neutralizer added cannot be accurately controlled by manual operation, which easily leads to excessive addition of neutralizer, resulting in waste; three neutralization tanks are used for segmented neutralization in the neutralization stage of calcium carbonate and calcium oxide, respectively. The segmented neutralization reaction increases the reaction time. Since the pH value in the two adjacent neutralization tanks is set as a gradient, and the pH value variation in the two adjacent neutralization tanks is set to be small, the amount of calcium carbonate and calcium oxide added can be more accurately controlled. Therefore, the three-stage neutralization tank forms a buffer between calcium carbonate and wastewater, which can be fully mixed, thereby improving the reaction efficiency and the utilization rate of calcium carbonate and calcium oxide;

[0016] 3. The segmented continuous neutralization method is adopted. The supernatant of the wastewater neutralized in the previous level is discharged into the next neutralization tank in turn. The neutralization reaction can also be carried out in the neutralization tank of the previous level while the neutralization tank of the next level is being neutralized. The gradient pH value setting is convenient for dispersing and reducing the amount of neutralizer added to each neutralization tank. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Usually, the components in the embodiments of the present application can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0018] Embodiment 1 to Embodiment 3

[0019] A staged neutralization process for comprehensive utilization of calcium carbonate powder and calcium oxide comprises the following steps:

[0020] Step 1: The wastewater is sequentially passed into the primary neutralization tank, the secondary neutralization tank, and the tertiary neutralization tank, and calcium carbonate is used for neutralization. The pH value in each neutralization tank is controlled respectively, so that the pH value of the wastewater discharged from the tertiary neutralization tank is 4.0-4.5;

[0021] Step 2: Discharge the tertiary wastewater into the fourth, fifth and sixth neutralization tanks in sequence, use calcium oxide for neutralization, and control the pH value in each neutralization tank respectively, so that the pH value of the wastewater discharged from the sixth neutralization tank is 8.0-9.0.

[0022] In this embodiment, the pH value of the primary neutralization tank in step 1 is controlled to be 3.0-3.5.

[0023] In this embodiment, the pH value of the secondary neutralization tank in step 1 is controlled to be 3.5-4.0.

[0024] In this embodiment, the pH value of the four-stage neutralization tank in step 2 is controlled to be 5.0-6.0.

[0025] In this embodiment, the pH value of the five-stage neutralization tank in step 2 is controlled to be 6.0-7.5.

[0026] The pH in each neutralization tank in Examples 1 to 3 is as shown in Table 1 below:

[0027] Table 1. Specific numerical values ​​of pH in each neutralization tank in Examples 1 to 3

[0028] Example 1 Example 2 Example 3 pH of primary neutralization tank 3 3.5 3.2 Secondary neutralization tank pH 3.5 4 3.7 pH of the third neutralization tank 4 4.5 4.2 pH of the fourth neutralization tank 5 6 5.5 Five-stage neutralization tank pH 6 7.5 7 Six-stage neutralization pool pH 8 9 8.5

[0029] Comparative Example 1

[0030] The pH in the first to sixth neutralization tanks of Comparative Example 1 is controlled in the same manner as in Example 1. The difference from Example 1 is that lime is used to neutralize the first to third neutralization tanks to the target pH.

[0031] Comparative Example 2

[0032] In Comparative Example 2, only two neutralization tanks, a primary neutralization tank and a secondary neutralization tank, are set. The target pH of the primary neutralization tank is 4.0 (consistent with the three-stage neutralization tank in Example 1), and the target pH of the secondary neutralization tank is 8.0 (consistent with the six-stage neutralization tank in Example 1). The primary neutralization tank of Comparative Example 2 uses calcium carbonate powder for neutralization, and the secondary neutralization tank of Comparative Example 2 uses lime for neutralization.

[0033] Table 2. Comparison of wastewater neutralization efficiency and consumed costs in Examples 1 to 3 and Comparative Examples 1 to 2

[0034]

[0035]

[0036] The above embodiments and comparative examples show that the present invention adopts three neutralization tanks for segmented neutralization in the stages of neutralization of calcium carbonate and calcium oxide. The segmented neutralization reaction increases the reaction time. Since the pH value in two adjacent neutralization tanks is set to a gradient, and the pH value variation range in two adjacent neutralization tanks is set to be small, the addition amount of calcium carbonate and calcium oxide can be more accurately controlled. Therefore, the three-stage neutralization tank allows calcium carbonate and wastewater to form a buffer, which can be fully mixed, thereby improving the reaction efficiency and the utilization rate of calcium carbonate and calcium oxide.

[0037] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.

Claims

1. A staged neutralization process for comprehensive utilization of calcium carbonate powder and calcium oxide, characterized in that: The following steps are involved: Step 1: The wastewater is sequentially passed into the primary neutralization tank, the secondary neutralization tank, and the tertiary neutralization tank, and calcium carbonate is used for neutralization. The pH value in each neutralization tank is controlled respectively, so that the pH value of the wastewater discharged from the tertiary neutralization tank is 4.0-4.5; Step 2: Discharge the tertiary wastewater into the fourth, fifth and sixth neutralization tanks in sequence, use calcium oxide for neutralization, and control the pH value in each neutralization tank respectively, so that the pH value of the wastewater discharged from the sixth neutralization tank is 8.0-9.

0.

2. The process for the comprehensive utilization of calcium carbonate powder and calcium oxide by staged neutralization according to claim 1, characterized in that: The pH value of the primary neutralization tank in step 1 is controlled to be 3.0-3.

5.

3. The process for the comprehensive utilization of calcium carbonate powder and calcium oxide by staged neutralization according to claim 1, characterized in that: The pH value of the secondary neutralization tank in step 1 is controlled to be 3.5-4.

0.

4. The process for the comprehensive utilization of calcium carbonate powder and calcium oxide by staged neutralization according to claim 1, characterized in that: The pH value of the four-stage neutralization tank in step 2 is controlled to be 5.0-6.

0.

5. The process for the comprehensive utilization of calcium carbonate powder and calcium oxide by staged neutralization according to claim 1, characterized in that: The pH value of the five-stage neutralization tank in step 2 is controlled to be 6.0-7.5.

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