CN111635066A - Method and device for recovering soluble silicon in silicon-containing wastewater - Google Patents
Method and device for recovering soluble silicon in silicon-containing wastewater Download PDFInfo
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Abstract
The application provides a method and system for recycling soluble silicon in silicon-containing wastewater, the silicon-containing wastewater is pretreated and then pumped into an electric flocculation device, silicon-containing floccules are generated in the wastewater after electric flocculation, the wastewater after electric flocculation is discharged into a precipitation device from a water outlet, a flocculation additive is added to accelerate coagulation and sedimentation of the silicon-containing floccules, and then the device is filtered, solid-liquid separation is performed to obtain the silicon-containing sediments and clarified wastewater, the silicon-containing sediments are dried to obtain silicon-containing byproducts, the clarified wastewater is pumped into a reverse osmosis system to be subjected to membrane concentration, the separated fresh water with high salt content and low salt content is obtained, the fresh water is recycled, and the desiliconization agent is added into the concentrated water to perform secondary desiliconization, so that the purpose. The method provided by the invention has high silicon removal efficiency, and is an efficient, economic and environment-friendly water treatment method. The system for recovering the soluble silicon in the silicon-containing wastewater provided by the invention has high equipment maturity, is easy to industrialize, and can realize silicon removal of wastewater, reduce the generation of silicon scale and reduce the equipment maintenance cost.
Description
Technical Field
The invention relates to the technical field of silicon-containing wastewater treatment, in particular to a method and a device for recovering soluble silicon in silicon-containing wastewater.
Background
With the progress and large-scale production of the electronic industry, silicon dioxide is used as a main raw material, and a large amount of silicon-containing wastewater is generated in the production processes of the production, alloy polishing, grinding industry and quartz sand industry. For example, during the processing of silicon wafers, up to 50-52% of the crystalline silicon is lost as silicon powder. The silicon powder in the silicon-containing wastewater is very fine, and the particle size is in the range of 0.1-1 mm. The raw materials of quartz sand and water glass are reacted to form silicon in the wastewater, and the nascent silicon dioxide is initially in a crystalline state in the reaction process to form a true solution, but the soluble silicon dioxide has great polymerization capacity and can be gradually combined together to form a typical silica colloidal solution with negative electricity. The colloidal silica and the soluble silica in the water can be mutually converted, the waste water is generally alkaline and has higher temperature, the colloidal silica in the waste water is easily converted into the soluble silica, and if the waste water is directly discharged into a natural water body, the silica is precipitated in a gel or floccule form along with the reduction of the pH and the temperature to form white water, pollute the water body and block a water channel.
Soluble silicon in wastewater is a potentially available resource. In the prior art, the treatment method of the silicon-containing wastewater is generally to add a proper flocculation additive, such as polyaluminium chloride, polymeric FeCl3, PP amide and the like, to flocculate and precipitate the wastewater, and then separate the precipitate. However, the method using the flocculating additive is high in cost, low in efficiency, poor in treatment effect and the like. Or coagulation desilication, reverse osmosis desilication, ultrafiltration desilication, ion exchange desilication and the like are adopted, wherein the coagulation desilication is simple and convenient to operate, simple in process and most widely applied.
However, the silicon coagulation is a physical and chemical method for removing silicon by utilizing the adsorption or condensation of oxides or hydroxides of certain metals on silicon, which is a non-deep silicon removal method and can be divided into magnesia-based silicon removal, aluminum salt silicon removal, iron salt silicon removal and lime silicon removal. 60% of colloidal silica can be removed by single coagulating sedimentation, the removal rate of dissolved silica is low, the requirement on reaction conditions is high, the silica removal effect of wastewater is poor, the dosage of a medicament is large, and the quality of effluent is unstable.
The reverse osmosis desilicication, ultrafiltration desilicication, ion exchange desilicication and other methods all need to use membranes with corresponding functions, and with the increase of the operation time of equipment, even if a scale inhibitor is added, a large amount of soluble silicon can be attached to and gathered on the pores of the membranes, and with the increase of a bridging effect, the membrane pores are finally blocked and lose efficacy, so that the treatment cost is increased, and the method cannot be suitable for the stable treatment of large-scale industrial wastewater.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
The invention provides a method and a device for removing silicon in wastewater by recovering soluble silicon in silicon-containing wastewater, which are characterized in that firstly, the conductivity of the silicon-containing wastewater is adjusted to be more than or equal to 5000 mu s/cm, better electrocoagulation concentration is ensured, the electrocoagulation efficiency is favorably improved, the energy consumption is saved, then the silicon-containing wastewater is pumped into an electrocoagulation device, silicon-containing floccules are generated in the electrocoagulation wastewater, the electrocoagulation wastewater is discharged into a sedimentation tank from a water outlet, flocculation additives are added to accelerate coagulation sedimentation of the silicon-containing floccules, then the silicon-containing floccules are filtered by a filtering device, solid-liquid separation is carried out to obtain silicon-containing sediments and clarified wastewater, and the silicon-containing sediments are dried to obtain a silicon-containing product I, wherein the main components. The clarified wastewater is pumped into a reverse osmosis system for membrane concentration, fresh water with high salt conductivity and low conductivity is obtained through separation, the fresh water is produced and recycled, a desiliconization agent is added into the high-salt-content concentrated water for secondary desiliconization, and a silicon-containing byproduct II (the main component is silicon dioxide) with the main component being silicon dioxide is recovered, so that the purpose of recovering silicon in the silicon-containing wastewater is achieved. In addition, the device can be matched with electrodialysis, an evaporator, membrane filtration and other devices to further recover fresh water resources or inorganic salt.
In order to achieve the above purpose of the present invention, the following technical solutions are adopted:
a method for recovering soluble silicon in silicon-containing wastewater comprises the following steps:
(a) adjusting the conductivity of the wastewater to be more than or equal to 5000 mus/cm, then carrying out electric flocculation treatment, adding a flocculation additive, carrying out solid-liquid separation after the silicon-containing floccule is coagulated and settled to obtain a silicon-containing sediment and clear wastewater, and drying the silicon-containing sediment to obtain a silicon-containing byproduct I;
the main components of the first silicon-containing byproduct comprise: one or more of aluminum silicate, iron silicate, copper silicate and zinc silicate;
optionally, the electric flocculation treatment is accompanied by stirring operation;
optionally, the silicon-containing wastewater is industrial production wastewater from silica production, alloy polishing, grinding industry and quartz sand finishing industry.
(b) Performing reverse osmosis treatment on the clarified wastewater obtained in the step (a), separating to obtain high-conductivity wastewater and fresh water with the conductivity of less than or equal to 100 mu s/cm, adding a silicon removing agent into the high-conductivity wastewater, performing solid-liquid separation to obtain a silicon-containing sediment and clarified wastewater, and drying the silicon-containing sediment to obtain a silicon-containing byproduct II with the main component of silicon dioxide;
wherein the conductivity of the high conductivity wastewater is 3-4 times that of the clarified wastewater obtained in step (a);
optionally, the voltage of the electric flocculation is 5-380V;
further, the time of the electric flocculation treatment is 1-150 minutes.
Optionally, the mass of the flocculation additive is 0.0001-0.01% of the wastewater;
further, the mass of the flocculation additive is 0.0004% -0.006% of the wastewater.
Optionally, the flocculation additive comprises one or a combination of several of an inorganic flocculation additive, a microbial flocculation additive, an organic-inorganic composite flocculation additive and an organic polymer flocculation additive;
further, the inorganic flocculation additive comprises FeCl3、Al2(SO4)3Inorganic polymer flocculation additive and AlCl3And Fe2(SO4)3One or a combination of several of them;
further, the inorganic polymer flocculation additive comprises one or a combination of more of polyaluminium chloride, polyferric sulfate, polyferric chloride and polyaluminium sulfate;
further, the organic-inorganic composite flocculation additive comprises one or a combination of two of polyaluminium chloride and polyferric sulfate.
Optionally, in step (a) and step (b), the drying temperature is 480 ℃ and optionally 180 ℃ and 420 ℃.
Optionally, the silicon removal agent accounts for 0.001% -0.01% of the high-conductivity wastewater by mass;
further, the mass of the silicon removing agent is 0.004-0.008% of that of the high-conductivity wastewater.
Optionally, the silicon removing agent is selected from CaO and Ca (OH)2、Mg(OH)2One or a combination of more of MgO and scale inhibitor;
further, the scale inhibitor is selected from one or a combination of more of high-silicon scale inhibitors, phosphine scale inhibitors and polycarboxylic acid scale inhibitors.
A system for recovering soluble silicon in silicon-containing wastewater comprises a conductivity regulating system, an electric flocculation system, a precipitation device, a first solid-liquid separation system, a reverse osmosis system and a second solid-liquid separation system which are sequentially connected;
the first solid-liquid separation system is also connected with a first drying device;
the second solid-liquid separation system is also connected with a second drying device;
further, the solid-liquid separation system is selected from one or more of an activated carbon filter, a plate-and-frame filter press, a centrifuge, a precision filter and a stack-screw filter press.
Optionally, the drying device is selected from one or a combination of several of a tray dryer, a centrifugal sprayer, an ebullated bed, a pressure sprayer, a flash dryer and a fluidized bed.
Optionally, the electric flocculation system comprises a flocculation device, at least one group of positive and negative electrode plates, an aeration device and a precipitation device;
further, the flocculation device and the precipitation device are made of insulating materials, and further, the insulating materials are selected from one or a combination of more of PP, PS, PC and PE;
furthermore, the positive and negative electrode plates are selected from one or a combination of a plurality of copper plates, zinc plates, iron plates and aluminum plates.
Compared with the prior art, the invention has the beneficial effects that:
(1) the method provided by the invention is suitable for soluble silicon-containing wastewater generated in various industrial production, has high silicon removal efficiency and low comprehensive treatment cost, and is an efficient, economic and environment-friendly method for treating silicon-containing wastewater.
(2) The device provided by the invention has high equipment maturity and is easy to industrialize.
(3) The technology provided by the invention can be combined with other equipment, so that zero discharge of waste water is realized simultaneously.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a schematic connection diagram of a system for recovering soluble silicon in silicon-containing wastewater according to an embodiment of the present invention.
Detailed Description
The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and the detailed description, but those skilled in the art will understand that the following described embodiments are some, not all, of the embodiments of the present invention, and are only used for illustrating the present invention, and should not be construed as limiting the scope of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The invention provides a method for recovering soluble silicon in silicon-containing wastewater, which comprises the following steps:
(a) firstly, adjusting the conductivity of the wastewater to be more than 5000 mus/cm, improving the efficiency and flocculation effect of electric flocculation, then carrying out electric flocculation treatment, adding a flocculation additive, carrying out solid-liquid separation after silicon-containing floccules are coagulated and settled to obtain silicon-containing sediment and clarified wastewater, and drying the silicon-containing sediment to obtain a silicon-containing byproduct I;
the main components of the first silicon-containing byproduct comprise: one or more of aluminum silicate, iron silicate, copper silicate and zinc silicate;
performing reverse osmosis treatment on the clarified wastewater obtained in the step (a), separating to obtain high-conductivity wastewater and fresh water with the conductivity of less than or equal to 100 mu s/cm, adding a silicon removing agent into the high-conductivity wastewater, performing solid-liquid separation to obtain a silicon-containing sediment and clarified wastewater, and drying the silicon-containing sediment to obtain a silicon-containing byproduct II with the main component of silicon dioxide;
wherein the conductivity of the high conductivity wastewater is 3-4 times that of the clarified wastewater obtained in step (a).
The application provides a method for recycling soluble silicon from high-silicon-content wastewater, and achieves the purpose of zero wastewater discharge. Solves the problems of comprehensive utilization and zero discharge of the silicon-containing wastewater generated in the prior production process. This application adopts electric flocculation to carry out the flocculation and precipitation to silicon-containing waste water and removes silicon, at first adjusts to the conductivity of waste water to more than 5000 mus/cm, and this is in order to improve electric flocculation's efficiency and effect, and the conductivity is too low, and electric flocculation effect is weak, needs bigger voltage and electric current just can carry out electric flocculation, and the running cost is high. Meanwhile, the auxiliary flocculation additive accelerates silicon precipitation, after the silicon is removed, the silicon removing agent is added for membrane separation after filtration separation, and a silicon-containing byproduct is recovered. And a small amount of concentrated solution can be subjected to evaporative crystallization and dehydration by combining equipment such as electrodialysis, an evaporator, membrane filtration and the like to obtain inorganic salt components in the wastewater, and clear water obtained by separation is recycled to achieve the aim of zero discharge.
In the existing membrane treatment concentration technology, along with the use of a membrane, silicon in wastewater can block pores of the membrane, so that the membrane loses corresponding functions. The application adopts two treatment processes of combining the electric flocculation and the flocculation additive and combining the reverse osmosis and the silicon removal agent, and can effectively recover the soluble silicon in the wastewater after solid-liquid separation and impurity removal, the recovery efficiency reaches up to 99.9 percent, and the soluble silicon can be utilized after being dried.
In the whole treatment process, the adjustment of the conductivity of the wastewater plays a key role in the silicon removal efficiency and the silicon removal method of the electric flocculation, floccules such as an aluminum-silicon complex, an iron-silicon complex and the like can be efficiently obtained after the conductivity suitable for the electric flocculation is adjusted, and flocculation additives are added to accelerate the sedimentation of the floccules so as to achieve the purpose of quickly separating and obtaining the wastewater with low silicon content. And adding the scale inhibitor to further reduce the silicon content in the wastewater with low silicon content so as to ensure that the membrane pores are not blocked and the continuous operation of an equipment system is ensured, and the whole treatment process has the advantages of low operation cost, small additive dosage, high cost-efficiency ratio, economy and environmental protection.
In some preferred implementation ranges, the wastewater treated by the method can come from different technical fields, such as industrial production wastewater of silica production, quartz sand finishing industry, grinding industry, alloy polishing and the like.
In some preferred embodiments, the electrocoagulation is carried out with stirring.
In some preferred ranges of practice, suitable voltage for electroflocculation can be adjusted to 5-380V, such as 5, 8, 10, 15, 25, 35, 45, 65, 85, 105, 125, 165, 185, 210, 225, 245, 265, 285, 305, 345, 355, 380V;
in some preferred ranges of practice, the time for the electrocoagulation treatment may be adjusted to be appropriate from 1 to 150 minutes, for example, 1, 6, 11, 16, 22, 28, 31, 42, 48, 52, 57, 62, 72, 75, 82, 85, 92, 102, 105, 112, 122, 125, 132, 135, 142, 145, 152 minutes.
In some preferred ranges of practice, the flocculating additive is present in an amount of 0.0001% to 0.01% by mass of the wastewater, e.g. 0.0001%, 0.0004%, 0.0008%, 0.002%, 0.003%, 0.005%, 0.01%;
in some preferred ranges of practice, the flocculating additive is present in an amount of 0.0004% to 0.006% by mass of the wastewater.
In some preferred embodiments, the flocculating additive, i.e., flocculant, comprises: inorganic flocculation additive, organic polymer flocculation additive, organic-inorganic composite flocculation additive and microorganism flocculation additive;
wherein the inorganic flocculating additive is selected from Al2(SO4)3、AlCl3、Fe2(SO4)3、FeCl3And one or more of inorganic polymer flocculation additives;
wherein, the inorganic polymer flocculation additive is selected from one or a combination of more of polyaluminium chloride, polyaluminium sulfate, polyferric chloride and polyferric sulfate;
wherein, the organic-inorganic composite flocculation additive is selected from one or the combination of two of polyaluminium chloride and polyferric sulfate.
In some preferred ranges of practice, the temperature of the drying in step (a) and step (b) is 100-.
In some preferred ranges of practice, the silicon removal agent is present in an amount of 0.001% to 0.01% by mass of the high conductivity wastewater, e.g., 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.008%, 0.009%, 0.01%;
furthermore, the mass of the silicon removing agent is 0.004-0.008% of the high-conductivity wastewater.
In some preferred ranges of practice, the silica remover is selected from CaO, MgO, Ca (OH)2、Mg(OH)2And one or more of scale inhibitors;
further, the scale inhibitor is selected from one or a combination of more of high silica scale inhibitors, phosphine scale inhibitors and polycarboxylic acid scale inhibitors.
A system for recovering soluble silicon in silicon-containing wastewater comprises a conductivity regulating system, an electric flocculation system, a precipitation device, a first solid-liquid separation system (a first drying device), a reverse osmosis system and a second solid-liquid separation system (a second drying device) which are sequentially connected;
in order to achieve better separation effect and improve separation efficiency, the solid-liquid separation system is selected from one or a combination of a plurality of plate-and-frame filter presses, precision filters, activated carbon filters, centrifuges and stack-screw filter presses.
In some preferred embodiments, the drying device may be selected from one or more of a fluidized bed, an ebullated bed, a flash dryer, a tray dryer, a pressure sprayer, and a centrifugal sprayer.
In some preferred implementation ranges, the electric flocculation system comprises a flocculation device, at least one set of positive and negative electrode plates, an aeration device and a precipitation device;
the flocculation device and the sedimentation device are made of insulating materials.
Wherein the insulating material is selected from one or a combination of more of PP, PS, PC and PE;
wherein, the positive and negative polar plates are selected from one or a combination of more of aluminum plates, copper plates, zinc plates and iron plates.
The second solid-liquid separation system can also be connected with an electrodialysis device and an evaporative crystallization device, and the aim of recovering inorganic salt is fulfilled by means of evaporative crystallization.
Example 1
The method for recovering soluble silicon in silicon-containing wastewater provided by the embodiment comprises the following steps:
(1) adjusting the conductivity of 1 ton of silicon-containing wastewater for producing silicon dioxide to be more than or equal to 5000 mus/cm, then carrying out electric flocculation treatment, beating an aeration device arranged in a groove for stirring, adjusting the voltage to be 5V, starting the electric flocculation device, generating about 1 mm of silicon-containing floccule in the wastewater after 120 minutes of treatment,
(2) adding 1 g of flocculating additive (polyaluminium chloride), coagulating and settling the silicon-containing floccule, filtering to obtain a silicon-containing sediment and clear wastewater, and drying the silicon-containing sediment in a boiling dryer at the temperature of 200 ℃ to obtain a silicon-containing byproduct I;
(3) performing reverse osmosis treatment on the clarified wastewater obtained in the step (2), and separating to obtain wastewater with the conductivity increased by 2-3 times and fresh water with the conductivity less than or equal to 100 mu s/cm;
(4) adding 10 g of MgO (silicon removing agent) into the high-conductivity wastewater, filtering to obtain a silicon-containing sediment, and drying the silicon-containing sediment in a boiling dryer at 200 ℃ to obtain a silicon-containing byproduct II.
Example 2
The method for recovering soluble silicon in silicon-containing wastewater provided by the embodiment comprises the following steps:
(1) adjusting the conductivity of silicon-containing wastewater generated by finish machining of 1 ton of quartz sand to be more than or equal to 5000 mu s/cm, then carrying out electric flocculation treatment, opening an aeration device arranged in a groove, adjusting the voltage to be 380V, starting the electric flocculation device, and after 1 minute of treatment, generating silicon-containing floccules of about 0.01 mm in the wastewater;
(2) adding 100 g of flocculating additive (polyferric sulfate), coagulating and settling the silicon-containing floccule, filtering to obtain a silicon-containing sediment and clear wastewater, and drying the silicon-containing sediment in a boiling dryer at the temperature of 200 ℃ to obtain a silicon-containing byproduct I;
(3) performing reverse osmosis treatment on the clarified wastewater obtained in the step (2), and separating to obtain wastewater with the conductivity increased by 2-3 times and fresh water with the conductivity less than or equal to 100 mu s/cm;
(4) 100 g of a silicon remover (Ca (OH)) was added to the high-conductivity wastewater2) And drying the silicon-containing sediment obtained after filtering and the clarified wastewater in a boiling dryer at the temperature of 200 ℃ to obtain a silicon-containing byproduct II.
Example 3
The method for recovering soluble silicon in silicon-containing wastewater provided by the embodiment comprises the following steps:
(1) adjusting the conductivity of silicon-containing wastewater generated by polishing 1 ton of alloy to be more than or equal to 5000 mu s/cm, then carrying out electric flocculation treatment, opening an aeration device arranged in a groove, adjusting the voltage to be 50V, starting the electric flocculation device, and generating silicon-containing floccules with the thickness of about 1 mm in the wastewater after 120 minutes of treatment;
(2) adding 10 g of flocculating additive (polymeric ferric sulfate), coagulating and settling the silicon-containing floccule, filtering to obtain a silicon-containing sediment and clear wastewater, and drying in a flash evaporation dryer at 120 ℃ to obtain a silicon-containing byproduct I;
(3) performing reverse osmosis treatment on the clarified wastewater obtained in the step (2), and separating to obtain wastewater with the conductivity increased by 2-3 times and fresh water with the conductivity less than or equal to 100 mu s/cm;
(4) adding 10 g of organic phosphonate scale inhibitor into the high-conductivity wastewater, filtering to obtain a silicon-containing sediment, and drying the clear wastewater in a flash dryer at 120 ℃ to obtain a silicon-containing byproduct II.
Comparative examples 1 to 4 the following operations were respectively changed in comparison with the examples, and the amounts of wastewater treated were respectively shown in Table 1:
comparative example 1: step (1) no electric flocculation operation is added;
comparative example 2: step (2) adding no flocculation additive;
comparative example 3: step (4), no silicon removing agent is added;
comparative example 4: and (3) adding no reverse osmosis operation.
Experimental examples results of wastewater treatment
The treatment results after treating wastewater for examples and comparative examples are shown in Table 1.
TABLE 1 results of treatment of silicon-containing wastewater
Experimental results show that the wastewater treated by the method provided by the application can effectively separate the silicon-containing byproducts and has high recovery efficiency. In addition, through comparison, the operations of electric flocculation, flocculation additives, silicon removal agents and reverse osmosis all influence the recovery efficiency of the silicon-containing byproducts in the recovered wastewater, and especially, the electric flocculation operation plays a vital role in zero discharge of the wastewater and recovery of inorganic salts.
While particular embodiments of the present invention have been illustrated and described, it will be appreciated that the above embodiments are merely illustrative of the technical solution of the present invention and are not restrictive; those of ordinary skill in the art will understand that: modifications may be made to the above-described embodiments, or equivalents may be substituted for some or all of the features thereof without departing from the spirit and scope of the present invention; the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention; it is therefore intended to cover in the appended claims all such alternatives and modifications that are within the scope of the invention.
Claims (10)
1. A method for recovering soluble silicon in silicon-containing wastewater is characterized by comprising the following steps:
(a) adjusting the conductivity of the wastewater to be more than or equal to 5000 mus/cm, then carrying out electric flocculation treatment, adding a flocculation additive, carrying out solid-liquid separation after the silicon-containing floccule is coagulated and settled to obtain a silicon-containing sediment and clear wastewater, and drying the silicon-containing sediment to obtain a silicon-containing byproduct I;
the main component of the silicon-containing byproduct I comprises one or a combination of more of aluminum silicate, iron silicate, copper silicate and zinc silicate;
optionally, the electric flocculation treatment is accompanied by stirring operation;
(b) performing reverse osmosis treatment on the clarified wastewater obtained in the step (a), separating to obtain high-conductivity wastewater and fresh water with the conductivity of less than or equal to 100 mu s/cm, adding a silicon removing agent into the high-conductivity wastewater, performing solid-liquid separation to obtain a silicon-containing sediment and clarified wastewater, and drying the silicon-containing sediment to obtain a silicon-containing byproduct II with the main component of silicon dioxide;
wherein the conductivity of the high conductivity wastewater is 3-4 times that of the clarified wastewater obtained in step (a);
optionally, the silicon-containing wastewater is industrial production wastewater from silica production, alloy polishing, grinding industry and quartz sand finishing industry.
2. The method for recovering soluble silicon in silicon-containing wastewater according to claim 1, wherein the voltage of the electrocoagulation is 5-380V;
optionally, the time of the electrocoagulation treatment is 1-150 minutes.
3. The method for recovering soluble silicon in silicon-containing wastewater according to claim 1, wherein the mass of the flocculation additive is 0.0001% -0.01% of the wastewater;
optionally, the flocculating additive is present in an amount of 0.0004% to 0.006% by mass of the wastewater.
4. The method for recovering the soluble silicon in the silicon-containing wastewater according to claim 1, wherein the flocculation additive comprises one or more of an inorganic flocculation additive, a microbial flocculation additive, an organic-inorganic composite flocculation additive and an organic polymer flocculation additive;
optionally, the inorganic flocculating additive comprises FeCl3、Al2(SO4)3Inorganic polymer flocculation additive and AlCl3And Fe2(SO4)3One or a combination of several of them;
optionally, the inorganic polymeric flocculation additive comprises one or a combination of polyaluminium chloride, polyferric sulfate, polyferric chloride and polyaluminium sulfate.
5. The method for recovering soluble silicon in silicon-containing wastewater as claimed in claim 1, wherein the temperature of the drying in step (a) and step (b) is 480 ℃ and optionally 420 ℃ and 180 ℃.
6. The method for recovering the soluble silicon in the silicon-containing wastewater as claimed in claim 1, wherein the mass of the silicon removing agent is 0.001% -0.01% of the high conductivity wastewater;
optionally, the silicon removal agent is 0.004-0.008% of the high-conductivity wastewater by mass.
7. The method for recovering soluble silicon in silicon-containing wastewater according to claim 1, wherein the silicon removing agent is selected from CaO, Ca (OH)2、Mg(OH)2One or a combination of more of MgO and scale inhibitor;
optionally, the scale inhibitor is selected from one or a combination of more of high silica scale inhibitors, phosphine series scale inhibitors and polycarboxylic acid scale inhibitors.
8. A system for recovering soluble silicon in silicon-containing wastewater, which is suitable for the method for recovering soluble silicon in silicon-containing wastewater according to any one of claims 1 to 7, and is characterized by comprising a conductivity regulating system, an electric flocculation system, a precipitation device, a first solid-liquid separation system, a reverse osmosis system and a second solid-liquid separation system which are connected in sequence;
the first solid-liquid separation system is also connected with a first drying device;
the second solid-liquid separation system is also connected with a second drying device;
optionally, the first solid-liquid separation system and/or the second solid-liquid separation system is/are one or more selected from the group consisting of an activated carbon filter, a plate-and-frame filter press, a centrifuge, a precision filter and a stacked-spiral filter press.
9. The method for recovering soluble silicon in silicon-containing wastewater according to claim 8, wherein the first drying device and/or the second drying device is/are selected from one or more of a tray dryer, a centrifugal sprayer, an ebullated bed, a pressure sprayer, a flash dryer and a fluidized bed.
10. The method for recovering the soluble silicon in the silicon-containing wastewater according to claim 8, wherein the electric flocculation system comprises a flocculation device, at least one set of positive and negative electrode plates, an aeration device and a precipitation device;
optionally, the flocculation device and the precipitation device are made of insulating materials, and further, the insulating materials are selected from one or a combination of more of PP, PS, PC and PE;
optionally, the positive and negative electrode plates are selected from one or a combination of copper plates, zinc plates, iron plates and aluminum plates.
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