CN114455739A - Method for harmless treatment of wastewater in electrolytic manganese metal production - Google Patents

Abstract

The invention discloses a method for harmlessly treating wastewater in electrolytic manganese metal production, which comprises the following steps: s1: collecting wastewater in electrolytic manganese production, and adding sulfuric acid to adjust the pH value to be not more than 3.5; s2: adding waste scrap iron into the waste water; s3: adding lime to adjust the pH value to 8.5-9.0, and aerating for 30-60 min; s4: adding a flocculating agent, aerating for 5-10 min, and then standing. The invention has the advantages of simple operation, convenient management, low investment and operation cost, and the like.

Description

Method for harmless treatment of wastewater in electrolytic manganese metal production

Technical Field

The invention relates to the technical field of electrolytic manganese production wastewater treatment and environmental protection, in particular to a method for harmlessly treating wastewater in electrolytic manganese metal production by using a high-efficiency flocculating agent.

Background

As an important metallurgical and chemical raw material, the manganese metal makes great contribution to the rapid development of the industry in China and has an important strategic position in national economy. Although the electrolytic manganese industry in China starts late, the electrolytic manganese industry develops quickly, and the electrolytic manganese industry becomes the biggest electrolytic manganese producing, exporting and consuming nation in the world at present. Pure manganese is mainly prepared by an electrolytic method in China, and more than 95 percent of electrolytic manganese enterprises use manganese carbonate ore as a raw material to prepare manganese by adopting acid leaching and double salt electrolysis processes. The main pollution sources generated in the production of electrolytic manganese are passivation wastewater, plate washing wastewater, workshop floor washing wastewater, filter cloth cleaning wastewater and plate frame cleaning wastewaterThe method comprises the following steps of cleaning waste water in the tank, leachate in a slag storage, surface runoff in a plant area, electrolytic tank cooling water and the like. 2-3.5 m of process wastewater can be generated when 1t of electrolytic manganese is produced³Discharging cooling water of 150-300 m³. The output of electrolytic manganese of 126 current electrolytic manganese enterprises in China exceeds 100 million t/a, and the generated wastewater is about 200-350 million t/a.

The electrolysis wastewater has complex water quality and low pH of the wastewater, generally about 4.5, and is acidic: the waste water contains heavy metal ions such as chromium, manganese and the like. Hexavalent chromium is typically present in the form of chromates and dichromates, with total manganese including tetravalent and divalent manganese, with divalent manganese being predominant. In addition, the wastewater also contains a certain amount of organic matters and NH₃N and the like, more suspended matters, higher chromaticity, and the water quality and the discharge standard of the electrolytic manganese wastewater are shown in the following table.

Electrolytic manganese wastewater quality and discharge standard

As can be seen from the above table, the electrolytic manganese wastewater contains a large amount of manganese ions and hexavalent chromium ions. Manganese ions in the wastewater can cause neurotoxicity, and hexavalent chromium ions can cause serious diseases of respiratory tract, skin and blood of people and can cause death of people when the diseases are serious. If the waste water is directly discharged into natural water without treatment, heavy metal pollution of the water can be caused, and serious harm is caused to human health and surrounding environment, so that the waste water must be discharged up to the standard through comprehensive treatment.

At present, in the aspect of treating electrolytic manganese wastewater in China, a flocculation sedimentation method and a micro-electrolysis method are researched more, and the flocculation sedimentation method is widely applied. However, the flocculation sedimentation method needs high pH value to facilitate sedimentation, so that the pH value of effluent is higher, and meanwhile, the flocculation sedimentation method has low chromium removal rate and cannot reach the national allowable discharge standard. The micro-electrolysis method is generally used for treating wastewater under an acidic condition, and easily causes large amount of dissolved iron filings or insignificant treatment effect. Liquid membrane method is studied more in the heavy metal separation field, but only a few waste water treatment technologies realize industrialization, and most separation technologies still stay in the laboratory research stage.

Meanwhile, the flocculation sedimentation method, the electrolysis method and the like have the defects of longer treatment process, harsh treatment conditions, higher cost, more waste residues, introduction of secondary pollution and the like; in short, the electrolytic manganese wastewater treatment methods are more, but the problems faced by industrial production are many, and research and improvement are needed continuously.

Disclosure of Invention

The invention overcomes the defects of the prior art, provides a method for harmlessly treating wastewater in electrolytic manganese metal production, and aims to solve the technical problems of poor wastewater treatment effect and easy introduction of secondary pollution in the electrolytic manganese metal production.

In view of the above problems of the prior art, according to one aspect of the present invention, to solve the above technical problems, the present invention adopts the following technical solutions:

a method for harmlessly treating wastewater in electrolytic manganese metal production comprises the following steps:

s1: collecting the wastewater in the electrolytic manganese production, and adding sulfuric acid to adjust the pH value to be not more than 3.5;

s2: adding waste scrap iron into the waste water;

s3: adding lime to adjust the pH value to 8.5-9.0, and aerating for 30-60 min;

s4: adding a flocculating agent, aerating for 5-10 min, and then standing.

In order to better realize the invention, the further technical scheme is as follows:

further, the adding amount of the scrap iron pieces in the step S2 is Cr in the wastewater⁶⁺The mass is 8-10 times.

Further, the aeration amount in the step S3 is every M³5-8M of wastewater³。

Further, the flocculant in the step S4 is PAC.

Further, the flocculant is added in the step S4 at a rate of every M³And adding 35-50 mg of flocculant into the wastewater.

Further, the standing time in the step S4 is 30 to 60 min.

Further, the scrap iron in the step S2 reacts for 30-60 min after being added.

Further, the scrap iron pieces are added in the step S2 and then reacted at normal temperature.

Further, still include:

s5: standing, directly discharging supernatant, filtering slurry and slag, directly discharging filtrate, and conveying slag to an anti-seepage slag storage.

Compared with the prior art, the invention has the following beneficial effects:

the method for harmlessly treating the wastewater in the production of the electrolytic manganese metal comprises the following steps:

(1) the method can simultaneously treat chromium, manganese, ammonia nitrogen, SS, COD and chromaticity in the electrolytic manganese wastewater, and completely reaches the national allowable discharge standard.

(2) Compared with other methods, the method does not need to adjust the pH value finally after the wastewater is treated, and the treated pH value is 8-8.7.

(3) The invention reasonably utilizes the waste scrap iron to reduce chromium, and simultaneously reacts the scrap iron with acid to generate bivalent iron ions which are oxidized into ferric iron, and finally the ferric hydroxide colloid with strong adsorbability is obtained, and the ferric hydroxide colloid is a prerequisite condition for the PAC flocculant to play a role.

(4) The invention has the advantages of simple operation, convenient management, low investment, low operating cost and the like.

Detailed Description

The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto.

A method for harmlessly treating wastewater in electrolytic manganese metal production comprises the following steps:

s1: collecting waste water in electrolytic manganese production, generally collecting the waste water to a liquid collecting tank, and then adding sulfuric acid to adjust the pH value to be not more than 3.5.

S2: adding waste scrap iron into the waste water.

Wherein the addition amount of the scrap iron isThe mass of Cr6+ in the wastewater is 8-10 times, generally, every M³Adding about 500g of waste scrap iron into the waste water, and reacting for 30-60 min at normal temperature.

S3: adding lime to adjust the pH value to 8.5-9.0, and aerating for 30-60 min, wherein the air flow is preferably per M³5 to 8M of wastewater³。

S4: adding a flocculating agent, aerating for 5-10 min, and then standing.

Wherein the flocculant can be PAC flocculant. The amount of flocculant added is preferably per M³And adding 35-50 mg of flocculant into the wastewater. The standing time can be 30-60 min.

S5: standing, directly discharging supernatant, filtering slurry and slag, directly discharging filtrate, and conveying slag to an anti-seepage slag storage.

The principle of the invention is that waste scrap iron with low price is used as a reducing agent to reduce hexavalent chromium into trivalent chromium, the PH value is adjusted to precipitate chromium and manganese, trace ammonia nitrogen is removed by aeration, simultaneously, ferrous iron in wastewater is oxidized into trivalent iron, the trivalent iron forms ferric hydroxide colloid, the ferric hydroxide colloid has strong adsorption property, and a PAC flocculating agent is matched to strengthen adsorption decoloration and flocculation, so that small particle precipitation is changed into large particle precipitation quickly, and the wastewater is clarified quickly.

Example 1

Effective volume of wastewater collection regulating pool is 100m³Adjusting pH to 3.5 with sulfuric acid per M³Waste iron filings 500g (Cr in waste water)⁶⁺56mg/L), and reacted at normal temperature for 40 min. Pumping into a reduction neutralization sedimentation tank. And (3) combining three pools of a reduction neutralization sedimentation tank, adding lime to adjust the pH value to 8.7, and aerating for 30 min. Gas amount is per M³Wastewater 5M³. Every M³Adding 35mg PAC flocculant into the wastewater, and aerating for 5-10 min. Standing for 30min, detecting water quality, directly discharging supernatant, filtering slurry and residue, directly discharging filtrate, and delivering residue to an impermeable residue storage.

Example 2

Example 2 differs from example 1 in that the wastewater collection and conditioning tank was adjusted to pH3.0 with sulfuric acid.

Example 3

Example 3 differs from example 1 in that per M³Waste iron filings 900g (Cr in waste water) is added into the waste water⁶⁺56 mg/L).

Example 4

Example 4 differs from example 1 in that per M³Adding waste scrap iron into the wastewater, and reacting for 60min at normal temperature.

Example 5

Example 5 differs from example 1 in that lime is added to adjust the PH to 8.0.

Example 6

Example 6 differs from example 1 in that the aeration was applied for 60 min. Gas amount is per M³10M of wastewater³。

Example 7

Example 7 differs from example 1 in that per M³50mg of PAC flocculant was added to the wastewater.

In the case of the example 8, the following examples are given,

the difference between this example and example 1 is that the aeration time after adding the flocculant is 10 min.

Example 9

This example differs from example 1 in that the final resting time was 60 min.

The following results were obtained from the tests of the quality of the treated wastewater from the production of electrolytic manganese metals according to examples 1 to 9 of the present invention:

the embodiments are described in a progressive manner in the specification, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

Reference throughout this specification to "one embodiment," "another embodiment," "an embodiment," etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment described generally in this application. The appearances of the same phrase in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the scope of the invention to effect such feature, structure, or characteristic in connection with other embodiments.

Although the invention has been described herein with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More specifically, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure and claims of this application. In addition to variations and modifications in the component parts and/or arrangements, other uses will also be apparent to those skilled in the art.

Claims (9)

1. A method for harmlessly treating wastewater in electrolytic manganese metal production is characterized by comprising the following steps:

s1: collecting the wastewater in the electrolytic manganese production, and adding sulfuric acid to adjust the pH value to be not more than 3.5;

s2: adding waste scrap iron into the waste water;

s3: adding lime to adjust the pH value to 8.5-9.0, and aerating for 30-60 min;

s4: adding a flocculating agent, aerating for 5-10 min, and then standing.

2. Electrolytic metal according to claim 1The method for innocent treatment of wastewater in manganese production is characterized in that the adding amount of the scrap iron in the step S2 is Cr in the wastewater⁶⁺The mass is 8-10 times.

3. The method of claim 1, wherein the aeration rate in step S3 is set to be per M³5-8M of wastewater³。

4. The method for harmlessly treating wastewater from the production of electrolytic manganese metal according to claim 1, wherein the flocculant in step S4 is PAC.

5. The method according to claim 1, wherein the flocculating agent is added in an amount of every M in step S4³And adding 35-50 mg of flocculant into the wastewater.

6. The method for the harmless treatment of wastewater in the electrolytic manganese metal production according to claim 1, wherein the standing time in the step S4 is 30-60 min.

7. The method for harmlessly treating the wastewater in the production of electrolytic manganese metal according to claim 1, wherein the scrap iron in step S2 is added and then reacted for 30-60 min.

8. The method for the innocent treatment of wastewater in the production of electrolytic manganese metal according to claim 7, characterized in that the scrap iron is added in step S2 and then reacted at normal temperature.

9. The method for harmlessly treating wastewater in the production of electrolytic manganese metal according to claim 1, further comprising:

s5: standing, directly discharging supernatant, filtering slurry and slag, directly discharging filtrate, and conveying slag to an anti-seepage slag storage.