CN102951752A - Filter-pressing action-based acid mine drainage treatment system and treatment method - Google Patents

Abstract

The invention discloses a mine acid wastewater treatment system and treatment method based on filter press, which includes a primary precipitation area (1), an alkaline material pool (2), a calcium carbonate neutralization pool (3), and a secondary precipitation area ( 4), the residue pool (5) and the filter press unit (6) process the wastewater through the steps of primary physical precipitation, primary chemical precipitation, secondary chemical precipitation, secondary physical precipitation and solid-liquid separation of the filter press unit. The beneficial effects of the present invention are: comprehensive utilization of physical and chemical treatment methods, treatment of waste water with too low pH value and high heavy metal content, effectively reducing the heavy metal content of acid mine waste water, reducing investment costs and improving treatment efficiency , At the same time, the filter press plays the role of treating both waste water and residues. The whole process can choose the type of filter press and the number of parallel installations according to the specific situation, without secondary pollution, high efficiency, large processing capacity, and automatic flushing , Easy to operate.

Description

Mine acid wastewater treatment system and treatment method based on filter press

technical field

The invention relates to a mine acid wastewater treatment system and a treatment method based on filter press action, and belongs to the technical field of mine acid wastewater treatment.

Background technique

Acid mine drainage (AMD) pollution is a worldwide problem, mainly mine water discharged from coal mines and metal mines, rainwater from waste rock yards, and ore washing and tailings discharged from concentrators Wastewater, which is characterized by: low pH value, high concentration of sulfate and soluble heavy metal ions. The direct discharge of acidic mine wastewater will cause great harm to the environment. Because heavy metal ions are different from organic substances, they cannot be biodegraded in the environment, so once they enter the environment, they will continue to accumulate and be difficult to remove, resulting in long-term environmental pollution. The low pH value of wastewater seriously threatens the growth of algae, phytoplankton and other organisms in rivers, and also pollutes groundwater. With the mining and utilization of mineral resources, our country is facing a serious problem of mine acid wastewater pollution.

The main ways for the formation of acidic wastewater in mines are: 1) During the mining process of ore deposits, a large amount of groundwater seeps into the mining face, and these pit waters are discharged to the surface, which is the main source of acidic wastewater; 2) In the process of ore processing, adding acidic chemicals The wastewater discharged from the beneficiation process is an important source of acid wastewater and harmful substances; 3) A large number of waste rocks and tailings containing sulfide minerals discharged during the mine production process are continuously mixed with air and water (or water vapor) when stacked in the open air Contact to generate metal ions and sulfate ions. During the rainy season, heavy metals and acid ions will dissolve in water bodies and enter rivers, lakes or seep into the ground with rainwater, thereby polluting surface water and groundwater.

过程后形成硫酸盐化合物而溶解于水中。如此，既增加了水中重金属离子的浓度，也使水体pH值降低。my country has a large number of mineral resources, and most of the minerals exist in the form of metal sulfides. During the mining process of these mineral resources, through the action of microorganisms and oxygen in the air,

After the process sulfate compounds are formed which dissolve in water. In this way, it not only increases the concentration of heavy metal ions in the water, but also reduces the pH value of the water body.

At present, there are mainly physical methods (adsorption method), chemical methods (flocculation method, precipitation method, chelating agent method), membrane treatment methods, and biological methods (constructed wetland method, microbial method) for the treatment of mine acid wastewater at home and abroad.

Adsorption method: This method uses the adsorption properties of certain substances with microporous structures (mainly activated carbon, etc.) to purify wastewater. The adsorption capacity of activated carbon to pollutants is limited, and the waste of saturated activated carbon without treatment will inevitably lead to problems such as waste of resources and environmental pollution.

Neutralization method: This method uses the principle of acid-base neutralization and precipitation. According to the fact that most heavy metal hydroxides are insoluble in water or slightly soluble in water, heavy metal ions form hydroxide by adding a certain amount of alkaline substances to acid mine water. It is a method to remove heavy metal ions in wastewater and increase the pH of wastewater. However, the amount of waste residue produced by the treatment is large, it is not easy to handle, and it may cause secondary pollution and other problems.

Micro-electrolysis flocculation method: This method is mainly based on Fe-C filler, and uses the electrochemical corrosion effect of iron filings in wastewater. The combined effect of coagulation, adsorption of new flocs and bed filtration. It also has some disadvantages: ①. The iron filings at the bottom of the electrolytic tower are easy to harden, which makes it difficult for Fe-C electron transfer, and makes H ⁺ → H ₂ on the iron particles wrap the iron particles, making it difficult to oxidize and dissolve, and reduce the treatment efficiency. Effect. ② The iron-carbon micro-electrolysis reaction needs to be carried out under acidic conditions (pH is generally 3-4), which makes the control of pH an important issue, while the discharge water is required to be neutral, and the contradiction between the two increases the operating cost. ③. In the micro-electrolysis process, the anode reaction: Fe-2e ^- → Fe ²⁺ , need to replenish iron scraps and replace residues in time, which increases the difficulty of operation.

Sulfide precipitation flotation method: It mainly uses the principle that the solubility of heavy metal sulfides in water is smaller than that of metal hydroxides, and by adding a certain amount of sulfide agent to precipitate heavy metals in the form of sulfides to reduce the concentration of heavy metals in water. In this method, vulcanizing agents such as H ₂ S and Na _s S are used, which easily cause secondary pollution of sulfides, the pH is not easy to control during the formation of sulfides, the cost of raw materials is high, and the sulfur content in the treated wastewater cannot reach National emission standards.

Polymer chelating agent method: a method of removing heavy metal ions in wastewater by using a polymer organic chelating agent to undergo a chelation reaction with metal ions to generate a stable and water-insoluble metal chelate. The polymer chelating agent used to treat waste water must meet the following conditions: ①The formed metal complex is insoluble in water and acid and alkali, and has a large radius and is easy to settle. ②The generated metal complex has low toxicity. ③ The stability should be relatively good, and it can exist stably. ④The addition amount of the chelating agent in the reaction process should be less, and the market price is cheap.

Constructed wetland method: A surface ecosystem similar to a swamp that is artificially constructed and operated, mainly using the physical, chemical, and biological synergies of the substrate-microbe-plant complex ecosystem to achieve a high degree of purification of sewage. But this method also has some limiting factors such as: some plants have a long growth cycle, slow growth, limited adsorption capacity, and most plants start to grow in neutral and low alkaline water bodies.

Microbial treatment method: Microbial treatment of acidic wastewater mainly uses sulfate-reducing bacteria (SRB) to dissimilate sulfate through the biological reduction reaction. Because this method is more difficult to operate, more complicated.

Membrane treatment method: Membrane separation technology is a separation technology that uses the osmotic pressure difference on both sides of the membrane to separate and concentrate ions in water under the action of unequal osmotic pressure and the selective permeability of the membrane. However, since industrial wastewater often contains substances such as acids and alkalis, the treatment conditions are relatively harsh. And the processing cost of this method is relatively high.

The above processing technologies have been applied to a certain extent due to their advantages, but they are also difficult to be popularized due to their respective shortcomings and limitations. Micro-electrolysis technology mainly uses iron filings and carbon particles as micro-electrolysis fillers, so after the water treatment reaction has been carried out for a period of time, adverse phenomena such as blockage and agglomeration appear. At the same time, there are problems before and after the micro-electrolysis reaction The problem of pH adjustment raises the cost. The application of the sulfide precipitation method is limited due to the serious secondary pollution of sulfur and the high cost of the vulcanizing agent. Membrane treatment technology can effectively treat mine acid wastewater to a certain extent, but the cost of membrane preparation and maintenance limits the widespread promotion of this technology. The microwave method has high treatment costs, high energy consumption, and expensive equipment maintenance costs, and it is mainly suitable for the treatment of wastewater containing organic matter. The adsorption method essentially relies on the adsorption of heavy metal ions on the active surface of the adsorbent to remove heavy metal ions. There are many kinds of adsorbents, the most common being activated carbon, but the adsorption rate of activated carbon is slow and the adsorption capacity is small, so it is not suitable for treating wastewater with high concentration of pollutants; and the regeneration procedure of activated carbon is complicated, which also limits its scope of use.

Most of these processes have high investment costs and a large amount of waste residue. The constructed wetland technology covers a large area and is not suitable for treating wastewater with a low pH value and high heavy metal content. Finding a low-cost and high-efficiency acid mine wastewater treatment process has become an urgent problem for industrial development.

Contents of the invention

The object of the present invention is to provide a filter press-based acid mine wastewater treatment system and treatment method that can treat wastewater with low pH value and high heavy metal content, low investment cost, high treatment efficiency, and no secondary pollution.

The purpose of the present invention is achieved by the following technical solutions: the mine acid wastewater treatment system based on filter press action, which includes a primary sedimentation area, an alkaline material pool, a calcium carbonate neutralization pool, a secondary sedimentation area, a residue pool and A filter press unit, wherein the wastewater outlet of the first-stage sedimentation zone is connected to the wastewater inlet of the alkaline material pool, the wastewater outlet of the alkaline material pool is connected to the wastewater inlet of the calcium carbonate neutralization tank, and the wastewater outlet of the calcium carbonate neutralization tank is connected to the The waste water inlet of the secondary sedimentation area is connected, the secondary sedimentation area is an overflow sedimentation tank, the first sedimentation area, the alkaline material pool, the calcium carbonate neutralization pool, and the residue outlet at the bottom of the secondary sedimentation area and the residue inlet of the residue pool The turbid liquid outlet on the lower side of the secondary sedimentation zone is connected to the residue outlet of the residue pool and the inlet of the filter press unit. The filter press unit is provided with two outlets, one of which flows back to the waste water inlet of the primary sedimentation zone.

The primary sedimentation zone is composed of two primary sedimentation tanks connected in series.

The alkaline material pool is composed of three carbon beds or soda lime beds connected in parallel.

The calcium carbonate neutralization tank is composed of three calcium carbonate beds connected in parallel.

A flocculant adding device is arranged in the secondary sedimentation zone.

The filter press unit is also provided with a mud cake outlet.

The mine acid wastewater treatment method based on filter press action, it comprises the following steps:

(1) Discharge the acidic wastewater from the mine into the first-level sedimentation zone composed of two first-level sedimentation tanks connected in series for primary physical precipitation, and the residue is discharged into the residue pool;

(2) Discharge the wastewater treated in the previous step into the alkaline material pool for primary chemical precipitation, use the adsorption performance and alkalinity of the material to remove part of the heavy metal ions in the wastewater for the first time, remove and increase the pH value of the water body, and discharge the residue into the residue pool;

(3) Discharge the wastewater treated in the previous step into the calcium carbonate neutralization pool for secondary chemical precipitation, use calcium carbonate to adjust the pH value of the wastewater again, reduce the content of heavy metals in part of the water and block the alkali from the alkaline material pool particles of abrasive materials, and the residue is discharged into the residue pool;

(4) Discharge the waste water treated in the previous step into the secondary sedimentation zone for secondary physical precipitation. The supernatant liquid in the secondary sedimentation zone is directly overflowed and discharged, and the turbid liquid in the lower layer is under the action of the flocculant, and the small particle suspended matter Agglomerates into lumpy polymer, and the residue is discharged into the residue pool;

(5) The turbid liquid discharged from the secondary sedimentation area and the residue in the residue pool are discharged into the filter press unit for solid-liquid separation, and the wastewater and residue are treated at the same time. When the effluent reaches the discharge standard, the standard water is discharged through the outlet of the filter press unit into the nearby river.

Since most of the heavy metal ions in acid mine wastewater (especially mine wastewater) are mostly adsorbed on suspended solid particles, the use of filtration methods can effectively reduce the content of acid mine wastewater. By adding a flocculant (polyaluminum chloride or polyferric chloride, etc.) to condense fine particles into agglomerated polymers, combined with the treatment method of pressure filtration, it can effectively intercept smaller suspended particles and effectively reduce heavy metals in acid mine wastewater content.

The beneficial effect of the present invention lies in: comprehensive utilization of physical and chemical treatment methods, treatment of waste water with too low pH value and high heavy metal content, effectively reducing the heavy metal content of acid mine waste water, reducing investment costs and improving treatment efficiency , At the same time, the filter press plays the role of not only treating waste water but also treating residues. The whole process can choose the type of filter press and the number of parallel installations according to the specific situation, without secondary pollution, high efficiency, large processing capacity, and automatic flushing , Easy to operate.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2 is the process schematic diagram of the treatment method of the present invention.

Among them, 1-first-level sedimentation area, 11-first-level sedimentation tank, 2-basic material pool, 22-carbon bed or soda lime bed, 3-calcium carbonate neutralization tank, 31-calcium carbonate bed, 4-secondary Sedimentation area, 41- flocculant adding device, 5- residue pool, 6- filter press unit.

Detailed ways

The technical solution of the present invention is further described below in conjunction with the accompanying drawings, but the scope of protection is not limited to the description.

As shown in Figure 1, the mine acid wastewater treatment system based on filter press, which includes a primary sedimentation area 1, an alkaline material pool 2, a calcium carbonate neutralization pool 3, a secondary sedimentation area 4, a residue pool 5, and a filter press unit 6 , wherein, the waste water outlet of the primary sedimentation zone 1 is connected with the waste water inlet of the alkaline material pool 2, the waste water outlet of the alkaline material pool 2 is connected with the waste water inlet of the calcium carbonate neutralization pool 3, and the waste water of the calcium carbonate neutralization pool 3 The outlet is connected to the waste water inlet of the secondary sedimentation zone 4, the secondary sedimentation zone 4 is an overflow sedimentation tank, the primary sedimentation zone 1, the alkaline material pool 2, the calcium carbonate neutralization tank 3 and the bottom of the secondary sedimentation zone 4 The residue outlet is connected to the residue inlet of the residue pool 5, and the turbid liquid outlet on the lower side of the secondary sedimentation zone 4 is connected to the residue outlet of the residue pool 5 and the inlet of the filter press unit 6. The filter press unit 6 is provided with two outlets, one of which is The outlet is returned to the waste water inlet of the primary sedimentation zone 1.

The primary sedimentation zone 1 is composed of two primary sedimentation tanks 11 connected in series.

The alkaline material pool 2 is composed of three carbon beds or soda lime beds 21 connected in parallel.

The calcium carbonate neutralization tank 3 is composed of three calcium carbonate beds 31 connected in parallel.

A flocculant adding device 41 is set in the secondary sedimentation zone 4 .

The filter press unit 6 is also provided with a mud cake outlet.

The treatment method of mine acid wastewater based on filter press, as shown in Figure 2, the white arrow in the figure indicates the treatment process of water in mine acid wastewater, and the black arrow indicates the treatment process of residue in mine acid wastewater, which includes the following steps:

(1) Discharge the acidic wastewater from the mine into the primary sedimentation zone 1 composed of two primary sedimentation tanks 11 connected in series for primary physical precipitation, and discharge the residue into the residue pool 5;

(2) Discharge the wastewater treated in the previous step into the alkaline material pool 2 for primary chemical precipitation, use the adsorption performance and alkalinity of the material to remove part of the heavy metal ions in the wastewater for the first time and increase the pH value of the water body, and discharge the residue into In the residue pool 5, the compactness of the alkaline material filling will filter out the large particles suspended in part of the water to a certain extent, which will help to further reduce the concentration of heavy metals in the waste water (because the heavy metal ions attached to the particles will desorb into the water body);

(3) Discharge the wastewater treated in the previous step into the calcium carbonate neutralization pool 3 for secondary chemical precipitation, use calcium carbonate to adjust the pH value of the wastewater again, reduce the content of heavy metals in part of the water and block the alkaline material from the pool 2 Alkaline material particles, the residue is discharged into the residue pool 5;

(4) Discharge the waste water treated in the previous step into the secondary precipitation zone 4 for secondary physical precipitation. The supernatant liquid in the secondary precipitation zone 4 is directly overflowed and discharged, and the turbid liquid in the lower layer is under the action of the flocculant. Suspended solids are condensed into agglomerated polymers, which can reduce the content of suspended particles in the water body to reduce the load of the filter press, and the agglomerated polymers are conducive to the process of pressing the filter, and the residue is discharged into the residue pool 5;

(5) Discharge the turbid liquid discharged from the secondary sedimentation area 4 and the residue in the residue pool 5 into the filter press unit 6 for solid-liquid separation, and treat the wastewater and residue at the same time. When the effluent reaches the discharge standard, the qualified water passes through the filter press unit 6 is discharged into a nearby river.

The filter press unit 6 has a good solid-liquid separation effect, and can better separate the suspended particles in the water body, and the filter press unit 6 has high efficiency, large processing capacity, multiple dehydration, strong dehydration ability, and low moisture content of mud cake , low power consumption, low-speed operation, no vibration, low noise, automatic flushing, convenient operation, etc. The whole process can choose the type of filter press according to the specific situation (mainly including plate and frame filter press, stacked screw press, etc.) filter, rotary drum sludge filter press and rotary disc microfilter, etc.) and the number of parallel installations.

Claims (7)

1. A mine acid wastewater treatment system based on filter press, characterized in that it includes a primary sedimentation area (1), an alkaline material pool (2), a calcium carbonate neutralization pool (3), and a secondary sedimentation area (4 ), a residue pool (5) and a filter press unit (6), wherein the wastewater outlet of the primary sedimentation zone (1) is connected to the wastewater inlet of the alkaline material pool (2), and the wastewater outlet of the alkaline material pool (2) It is connected to the wastewater inlet of the calcium carbonate neutralization tank (3), and the wastewater outlet of the calcium carbonate neutralization tank (3) is connected to the wastewater inlet of the secondary sedimentation zone (4), which is an overflow sedimentation pool, the residue outlet at the bottom of the primary sedimentation area (1), alkaline material pool (2), calcium carbonate neutralization pool (3) and the bottom of the secondary sedimentation area (4) is connected to the residue inlet of the residue pool (5), and the second The turbid liquid outlet on the lower side of the first-stage sedimentation zone (4) is connected to the residue outlet of the residue pool (5) and the inlet of the filter press unit (6). The filter press unit (6) is provided with two outlets, one of which flows back to a The waste water inlet of the stage sedimentation zone (1). 2. The acidic mine wastewater treatment system based on filter press according to claim 1, characterized in that: said primary sedimentation zone (1) is composed of two primary sedimentation tanks (11) connected in series. 3. The acidic mine wastewater treatment system based on filter press according to claim 1, characterized in that: the alkaline material pool (2) consists of three carbon beds or soda lime beds (21) connected in parallel composition. 4. The acidic mine wastewater treatment system based on filter press according to claim 1, characterized in that: the calcium carbonate neutralization pool (3) is composed of three calcium carbonate beds (31) connected in parallel. 5 . The acidic mine wastewater treatment system based on filter press according to claim 1 , characterized in that: a flocculant adding device ( 41 ) is set in the secondary sedimentation area ( 4 ). 6. The acid mine wastewater treatment system based on filter press according to claim 1, characterized in that: the filter press unit (6) is also provided with a mud cake outlet. 7. The mine acid wastewater treatment method based on filter press, is characterized in that: it comprises the following steps: (1) Discharge the acidic wastewater from the mine into the primary sedimentation zone (1) composed of two primary sedimentation tanks (11) connected in series for primary physical precipitation, and discharge the residue into the residue pool (5); (2) Discharge the wastewater treated in the previous step into the alkaline material pool (2) for primary chemical precipitation, use the adsorption performance and alkalinity of the material, remove part of the heavy metal ions in the wastewater for the first time, remove and increase the pH value of the water body, and the residue into the residue pool (5); (3) Discharge the wastewater treated in the previous step into the calcium carbonate neutralization tank (3) for secondary chemical precipitation, and use calcium carbonate to adjust the pH value of the wastewater again, while reducing the content of heavy metals in part of the water and blocking them from alkaline materials. Alkaline material particles in the pool (2), and the residue is discharged into the residue pool (5); (4) Discharge the waste water treated in the previous step into the secondary sedimentation zone (4) for secondary physical precipitation. The supernatant liquid in the secondary sedimentation zone (4) is directly overflowed and discharged, and the turbid liquid in the lower layer is under the action of flocculant Under this condition, the suspended solids of small particles condense into lumpy polymers, and the residue is discharged into the residue pool (5); (5) Discharge the turbid liquid discharged from the secondary sedimentation area (4) and the residue in the residue pool (5) into the filter press unit (6) for solid-liquid separation, and treat the waste water and residue at the same time. When the effluent reaches the discharge standard, it is up to the standard The water is discharged into the nearby river through the outlet of the filter press unit (6).

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