Background technology
Elementary silicon is as important photoelectric material, semiconductor material, and the status of its strategic resource is day by day obvious, and its global demand amount also constantly increases.At photoelectricity, in semiconductor industry, elemental silicon body is needed to cut into satisfactory silicon chip, current polysilicon mainly adopts multi-wire saw technology, in cutting process, the silicon material of about 50% is infiltrated in the cutting fluid be made up of polyoxyethylene glycol (PEG) cutting fluid and carborundum powder (SiC) abrasive material, make the composition of micro mist in cutting fluid, particle diameter, hardness does not all meet standard, cutting ability is caused to decline, can not reuse, therefore need constantly to discharge old cutting fluid in cutting process, and constantly supplement new cutting fluid, this creates the terminal a large amount of cutting waste liquors.
Cutting waste fluid is dark thick shape suspension, and main ingredient and content are: polyoxyethylene glycol (PEG), 40% ~ 50%; Silicon carbide (SiC), 23% ~ 33%; Silicon (Si), 20% ~ 24%; Iron filings (Fe), 2. 5% ~ 3. 0%.Wherein, the raw material of PEG extract in oil, repolymerization forms, molecular structure stabilized, not easily decomposes, very easily water-soluble, biological oxygen demand (BOD) is low, not easily degrades at occurring in nature, and its COD (chemical oxygen demand (COD)) value substantially exceeds wastewater discharge standard, as without special processing, flow into physical environment and will cause huge pollution.SiC and Si is important industrial raw material, all belongs to Nonrenewable resources.Produce in SiC raw material process and will consume the huge energy, country now limits this new industrial project.Si is wherein the high-purity silicon powder cutting, if directly discharge can cause the waste of environmental pollution and silicon materials.
At present for the process of this waste water, there are two kinds of thinkings: one is process rear discharge up to standard.Common method has microbial method, advanced oxidation processes etc., for this important waste water containing PEG, and microbial method complex process, processing efficiency is low, poor processing effect, hardly may be up to standard; Advanced oxidation processes treatment effect is better, but working cost is higher, and technology controlling and process is complicated; Other conventional sewage water treatment method is also difficult to be suitable for; Another kind of thinking is recycled waste liquid classification, because PEG, SiC and Si in waste water are important industrial raw material, and wherein polyoxyethylene glycol (PEG) market price 12 yuan of per kilograms, SiC market price 24 yuan of per kilograms, Si market price 140 yuan of per kilograms.Therefore, classification is reclaimed and is utilized silicon cutting waste liquor for economizing on resources, protection of the environment, increases economic efficiency significant, and had comparatively ripe process recovery technology abroad, domestic this respect technology is also immature, is mostly in conceptual phase.
Domestic existing process recovery technology, as a kind of zero-emission process for photovoltaic wastewater (CN 102557291A), system flow is long, complex process, investment are excessive, is difficult to realize practical implementation; A kind of process, containing the method (CN 1023722388A) of polyoxyethylene glycol waste water, adopts flocculation sediment, Fendon oxidation technology, and processed waste water need enter waste water treatment plant's process again, cost of use higher, and and be not suitable for the process of polysilicon waste water; From silicon chip cutting processing byproduct, reclaim the method (CN101244823A) of silicon carbide, this patented method adopts centrifugal solid-liquid to be separated, the silicon carbide in a Recycling of waste liquid, and polyoxyethylene glycol and the higher silicon of recovery value do not relate to;
Existing recovery technology subject matter is: 1. solid-liquid separation effect is not good, often need through stage trapping, as: centrifugation, sloping plate deposition, filtration, press filtration etc., isolated PEG liquid contains the impurity of part lightweight, needs through ability reuse of further purifying; 2. the complicated and less effective of SiC and Si sepn process, needs to use various chemical medicaments or through multiple physical process, lack a kind of simple and effective separation method.
Summary of the invention
Technical problem to be solved by this invention is efficient treatment for reuse technology, thoroughly can solve the not good problem of solid-liquid separation effect, for this reason, provides a kind of polysilicon wastewater treatment equipment and method.
It is as follows that the present invention solves the problems of the technologies described above taked technical scheme:
A kind of polysilicon wastewater treatment equipment, comprising: ceramic membrane system;
Wherein, described ceramic membrane system, comprises feed liquid case, charging pump, recycle pump, ceramic membrane, permeate case and multiple connecting tube, wherein, connecting tube is also provided with pressure regulator valve door and/or instrument.
Further, preferably, the shape of described ceramic membrane is tubular type multistage bending hollow structure, and fenestra is less than 1 μm.
Further, preferably, described ceramic membrane is made by by titanium dioxide and zirconium dioxide material.
Further, preferably, be also connected with liquid trap by pipeline, comprise:
Be separated cavity and coupled fluid reservoir, flow supply pump, wherein, described flow supply pump is located at and is separated between cavity and described fluid reservoir.
Further, preferably, the liquid-inlet of described separation cavity opens the lower position in described separation cavity.
Further, preferably, described liquid is pure water or calcium chloride or sodium chloride solution.
A kind of polysilicon method of wastewater treatment, comprising:
(1) after supercharging, enter polysilicon waste liquid into ceramic membrane system, under 0.20MPa-0.55MPa pressure, carry out solid-liquid separation, isolate polyoxyethylene glycol fluid storage and produce in order to reuse, the solidliquid mixture that sub-department goes out enters step (2);
(2) the solidliquid mixture pure water rinsing gone out by ceramic membrane systematic position is clean, comprised: the solid mixture of SiC, Si, Fe and impurity, this solid mixture is added in hydrochloric acid and carry out stirring and cleaning, isolate the composite grain thing of solid SiC, solid Si and impurity;
(3) described solid SiC and Si composite grain thing are added fluid separator, control fluid separator flow velocity, make SiC and Si layering, and collect SiC and Si of layering respectively, solid SiC, solid Si that part is in admixture are not then separated with impurity.
Further, preferably, after step (3), also comprise: the Si founding after being separated is purified, to obtain solar-grade polysilicon; And/or; To be separated after SiC drying after and carry out micro-powder graded separation, by size select reuse.
Further, preferably, in step (2), the temperature of described hydrochloric acid 30 DEG C-45 DEG C, concentration 10%-30%, and, also to carry out stirring 30-90 minute in step (2).
Further, preferably, in step (3), described fluid separator flow velocity is 40m/h-60 m/h.
After this invention takes such scheme, there is following superiority:
1. former waste liquid is without any process, direct weighting be separated, do not need to add any chemical, isolated PEG purity reaches 99.7%, and process is simple and reliable, once just can complete PEG be separated and through purification process, the PEG rate of recovery reaches 92%;
2. SiC and the Si fluid separator technology of novelty, not only simple to operate, and have good separating effect, and the Si rate of recovery reaches as high as 85%, the SiC rate of recovery more than 90%.Because SiC with the Si mixture of separating interface can continue to be separated in being separated next time, be separated number of times in theory more, separation rate is higher.
3. the waste liquid that the present invention need process is turned waste into wealth, and not only achieves " zero " discharge of pollutent, has again very high economic benefit simultaneously.
Other features and advantages of the present invention will be set forth in the following description, and, partly become apparent from specification sheets, or understand by implementing the present invention.Object of the present invention and other advantages realize by structure specifically noted in write specification sheets, claims and accompanying drawing and obtain.
Embodiment
Describe embodiments of the present invention in detail below with reference to drawings and Examples, to the present invention, how utilisation technology means solve technical problem whereby, and the implementation procedure reaching technique effect can fully understand and implement according to this.It should be noted that, only otherwise form conflict, each embodiment in the present invention and each feature in each embodiment can be combined with each other, and the technical scheme formed is all within protection scope of the present invention.
In addition, can perform in the computer system of such as one group of computer executable instructions in the step shown in the schema of accompanying drawing, and, although show logical order in flow charts, but in some cases, can be different from the step shown or described by order execution herein.
As shown in Figure 1, described polysilicon method of wastewater treatment, the present invention carries out according to following step:
(1) after supercharging, enter polysilicon waste liquid into ceramic membrane system, under 0.20MPa-0.55MPa pressure, carry out solid-liquid separation, isolate polyoxyethylene glycol fluid storage and produce in order to reuse, the solidliquid mixture that sub-department goes out enters step (2);
(2) the solidliquid mixture pure water rinsing gone out by ceramic membrane systematic position is clean, comprised: the solid mixture of SiC, Si, Fe and impurity, this solid mixture is added in hydrochloric acid and carry out stirring and cleaning, isolate the composite grain thing of solid SiC, solid Si and impurity;
(3) described solid SiC and Si composite grain thing are added fluid separator, control fluid separator flow velocity, make SiC and Si layering, and collect SiC and Si of layering respectively, solid SiC, solid Si that part is in admixture are not then separated with impurity.
Further, preferably, after step (3), also comprise: the Si founding after being separated is purified, to obtain solar-grade polysilicon; And/or; To be separated after SiC drying after and carry out micro-powder graded separation, by size select reuse.
Further, preferably, in step (2), the temperature of described hydrochloric acid 30 DEG C-45 DEG C, concentration 10%-30%, and, also to carry out stirring 30-90 minute in step (2).
Further, preferably, in step (3), described fluid separator flow velocity is 40m/h-60 m/h.
Wherein, in a more specific embodiment, operate according to step below:
The first step: waste liquid is entered after supercharging into ceramic membrane system, solid-liquid separation is carried out under 0.20MPa-0.55MPa pressure, ceramic membrane system is Millipore filtration techniques, effective pore size filter is less than 1 μm, under pressure-driven, PEG liquid in waste liquid passes through micropore, solid particulate in waste liquid then cannot pass through, sepn process is carried out at normal temperatures, do not need to add any chemical agent yet, there is not any phase transformation in whole process, isolated PEG purity liquid reaches 99.7%, reach cutting production requirement completely, directly can store and produce in order to reuse, the PEG rate of recovery is greater than 92%,
Second step: the concentrated mud pure water rinsing gone out by ceramic membrane systematic position is clean, obtain the solid of SiC, Si, Fe and minute quantity impurity, this solids is added temperature 30 DEG C-45 DEG C, stirring and washing 30-90 minute in the hydrochloric acid of concentration 10%-30%, Fe and a small amount of impurity and hydrochloric acid reaction, be dissolved in hydrochloric acid and be removed, after overpickling, clean by pure water rinsing, gained solid particulate is SiC and Si;
3rd step: the composite grain thing obtained in upper step is added fluid separator, controlling fluid separator flow velocity is 40m/h-60 m/h, wherein in fluid separator, liquid used is pure water or calcium chloride, sodium chloride solution, due to different (the SiC 3.2g/cm3 of SiC with Si density, Si 2.4g/cm3), when the liquid in fluid separator is from bottom to top with certain flow rate, composite grain thing entirety is in suspended state, the little Si of density is suspended in upper strata, the SiC that density is large is suspended in lower floor, at this moment fluid flowing is stopped, the composite grain suspended just delaminating deposition gets off, separation can be completed, collect SiC respectively, Si, the mixture of a small amount of SiC and Si is had in the middle of fluid separator separating layer, this part mixture can be collected in addition, be separated again when next mixture separation, SiC and the Si purity collected can be ensured like this, simultaneously after separating for several times, separation rate will improve,
4th step: the Si founding of collecting purified, can obtain solar-grade polysilicon, the Si rate of recovery reaches as high as 85%; 5th step: carry out micro-powder graded separation by after SiC drying, selects reuse by size, the rate of recovery more than 90%.
Wherein, as shown in Figures 2 and 3, the present embodiment also discloses a kind of polysilicon wastewater treatment equipment, wherein, the inventive point of the present embodiment is mainly ceramic membrane system and fluid separator, therefore, mainly illustrate its structure in figs. 2 and 3, other parts can adopt existing parts, are not described in detail at this, and these are all that those skilled in the art can know.
As shown in Figure 2, described ceramic membrane system, comprises feed liquid case 11, charging pump 12, recycle pump 13, ceramic membrane 14, permeate case 15 and multiple connecting tube, wherein, connecting tube is also provided with pressure regulator valve door and/or instrument.
Further, preferably, the shape of described ceramic membrane is tubular type multistage bending hollow structure, and fenestra is less than 1 μm.
Further, preferably, described ceramic membrane is made by by titanium dioxide and zirconium dioxide material.
Further, preferably, be also connected with liquid trap by pipeline, comprise:
Be separated cavity 31 and coupled fluid reservoir 33, flow supply pump 32, wherein, described flow supply pump is located at and is separated between cavity and described fluid reservoir.
Further, preferably, the liquid-inlet of described separation cavity opens the lower position in described separation cavity, and wherein, up, large density separation thing 35, in below, can exist in bottom and not be separated mixture completely little density separation thing 34.
Further, preferably, described liquid is pure water or calcium chloride or sodium chloride solution, more particularly, in described fluid separator, liquid used enters separator from the bottom to top, by regulating flow rate of liquid in fluid separator, be that mixture to be separated is in suspended state, and fluid separator liquid used is pure water or certain density calcium chloride, sodium chloride solution.
Describe two embodiments below in conjunction with accompanying drawing, the present invention is described in detail.
One of embodiment 1, treatment process, according to carrying out with following step:
The first step: the waste liquid collected is supplied ceramic membrane system through fresh feed pump, ON cycle pump, by regulating fresh feed pump late gate, recycle pump late gate and concentrated solution reverse flow valve, controlling ceramic membrane system inlets pressure is 0.55MPa, ceramic membrane system outlet pressure is 0.40MPa, it is 0.14 μm that ceramic membrane system loads membrane filtration aperture, under pressure-driven, PEG liquid in waste liquid is by ceramic membrane micropore, solid particulate in waste liquid cannot pass through, by through PEG liquid collecting store, after appearing without PEG liquid, collection enriching slurry;
Second step: the enriching slurry pure water rinsing gone out by ceramic membrane systematic position is clean, obtain the solid of SiC, Si, Fe and minute quantity impurity, this solids is added temperature 30 DEG C, stirring and washing 90 minutes in the hydrochloric acid of concentration 10%, removing Fe and a small amount of impurity, after overpickling, clean by pure water rinsing, gained solid particulate is SiC and Si;
3rd step: the composite grain thing obtained in upper step is added fluid separator, controlling fluid separator flow velocity is 60 m/h, wherein in fluid separator, liquid used is pure water, when composite grain thing is all in suspended state, quick stopping fluid separator water inlet, mixture rapid subsidence is got off, collects the Si on upper strata and the SiC of lower floor respectively;
4th step: the Si founding of collecting is purified, can solar-grade polysilicon be obtained;
5th step: carry out micro-powder graded separation by after SiC drying, selects reuse by size;
Embodiment 2, treatment process two, according to carrying out with following step:
The first step: the waste liquid collected is supplied ceramic membrane system through fresh feed pump, ON cycle pump, by regulating fresh feed pump late gate, recycle pump late gate and concentrated solution reverse flow valve, controlling ceramic membrane system inlets pressure is 0.35MPa, ceramic membrane system outlet pressure is 0.2MPa, it is 0.3 μm that ceramic membrane system loads membrane filtration aperture, under pressure-driven, PEG liquid in waste liquid is by ceramic membrane micropore, solid particulate in waste liquid cannot pass through, by through PEG liquid collecting store, after appearing without PEG liquid, collection enriching slurry;
Second step: the enriching slurry pure water rinsing gone out by ceramic membrane systematic position is clean, obtain the solid of SiC, Si, Fe and minute quantity impurity, this solids is added temperature 40 DEG C, stirring and washing 60 minutes in the hydrochloric acid of concentration 20%, removing Fe and a small amount of impurity, after overpickling, clean by pure water rinsing, gained solid particulate is SiC and Si;
3rd step: the composite grain thing obtained in upper step is added fluid separator, controlling fluid separator flow velocity is 50 m/h, wherein in fluid separator, liquid used is 20% sodium chloride solution, when composite grain thing is all in suspended state, quick stopping fluid separator water inlet, mixture rapid subsidence is got off, collects the Si on upper strata and the SiC of lower floor respectively;
4th step: the Si founding of collecting is purified, can solar-grade polysilicon be obtained;
5th step: carry out micro-powder graded separation by after SiC drying, selects reuse by size;
Embodiment 3, treatment process three, according to carrying out with following step:
The first step: the waste liquid collected is supplied ceramic membrane system through fresh feed pump, ON cycle pump, by regulating fresh feed pump late gate, recycle pump late gate and concentrated solution reverse flow valve, controlling ceramic membrane system inlets pressure is 0.25MPa, ceramic membrane system outlet pressure is 0.1MPa, it is 0.8 μm that ceramic membrane system loads membrane filtration aperture, under pressure-driven, PEG liquid in waste liquid is by ceramic membrane micropore, solid particulate in waste liquid cannot pass through, by through PEG liquid collecting store, after appearing without PEG liquid, collection enriching slurry;
Second step: the enriching slurry pure water rinsing gone out by ceramic membrane systematic position is clean, obtain the solid of SiC, Si, Fe and minute quantity impurity, this solids is added temperature 45 C, stirring and washing 30 minutes in the hydrochloric acid of concentration 30%, removing Fe and a small amount of impurity, after overpickling, clean by pure water rinsing, gained solid particulate is SiC and Si;
3rd step: the composite grain thing obtained in upper step is added fluid separator, controlling fluid separator flow velocity is 40 m/h, wherein in fluid separator, liquid used is 30% calcium chloride solution, when composite grain thing is all in suspended state, quick stopping fluid separator water inlet, mixture rapid subsidence is got off, collects the Si on upper strata and the SiC of lower floor respectively;
4th step: the Si founding of collecting is purified, can solar-grade polysilicon be obtained;
5th step: carry out micro-powder graded separation by after SiC drying, selects reuse by size;
The present invention has following superiority:
Ceramic membrane solid-liquid separation technique, former waste liquid without any process, direct weighting be separated, do not need to add any chemical, isolated PEG purity reaches 99.7%, and process is simple and reliable, once just can complete PEG be separated and through purification process, the PEG rate of recovery reaches 92%;
2. SiC and the Si fluid separator technology of novelty, not only simple to operate, and have good separating effect, and the Si rate of recovery reaches as high as 85%, the SiC rate of recovery more than 90%.Because SiC with the Si mixture of separating interface can continue to be separated in being separated next time, be separated number of times in theory more, separation rate is higher.
3. the waste liquid that the present invention need process is turned waste into wealth, and not only achieves " zero " discharge of pollutent, has again very high economic benefit simultaneously:
|
Market price (unit/kilogram) |
Recovery article valency (unit/kilogram) |
Polyoxyethylene glycol (PEG) |
12 |
12 |
Silicon carbide (SiC) |
24 |
18 |
Silicon (Si) |
140 |
140 |
It should be noted that, for aforesaid method embodiment, in order to simple description, therefore it is all expressed as a series of combination of actions, but those skilled in the art should know, the application is not by the restriction of described sequence of operation, because according to the application, some step can adopt other orders or carry out simultaneously.Secondly, those skilled in the art also should know, the embodiment described in specification sheets all belongs to preferred embodiment, and involved action and module might not be that the application is necessary.
Those skilled in the art should understand, the embodiment of the application can be provided as method, system or computer program.Therefore, the application can adopt the form of complete hardware embodiment, completely software implementation or the embodiment in conjunction with software and hardware aspect.
Last it is noted that the foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, although with reference to previous embodiment to invention has been detailed description, for a person skilled in the art, it still can be modified to the technical scheme described in foregoing embodiments, or carries out equivalent replacement to wherein portion of techniques feature.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.