CN110642544A - Method for rapidly preparing lightweight aggregate by using dredged sludge - Google Patents
Method for rapidly preparing lightweight aggregate by using dredged sludge Download PDFInfo
- Publication number
- CN110642544A CN110642544A CN201911033679.3A CN201911033679A CN110642544A CN 110642544 A CN110642544 A CN 110642544A CN 201911033679 A CN201911033679 A CN 201911033679A CN 110642544 A CN110642544 A CN 110642544A
- Authority
- CN
- China
- Prior art keywords
- sphere
- dredged sludge
- steam
- lightweight aggregate
- sludge
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/009—Porous or hollow ceramic granular materials, e.g. microballoons
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B18/02—Agglomerated materials, e.g. artificial aggregates
- C04B18/027—Lightweight materials
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B33/00—Clay-wares
- C04B33/02—Preparing or treating the raw materials individually or as batches
- C04B33/13—Compounding ingredients
- C04B33/132—Waste materials; Refuse; Residues
- C04B33/1321—Waste slurries, e.g. harbour sludge, industrial muds
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B33/00—Clay-wares
- C04B33/32—Burning methods
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/60—Production of ceramic materials or ceramic elements, e.g. substitution of clay or shale by alternative raw materials, e.g. ashes
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Civil Engineering (AREA)
- Dispersion Chemistry (AREA)
- Environmental & Geological Engineering (AREA)
- Treatment Of Sludge (AREA)
Abstract
The invention provides a method for quickly preparing lightweight aggregate by using dredged sludge, which comprises the following steps: step S1, mixing the dredged sludge raw material with a homogenizing agent to obtain mixed slurry; step S2, pelletizing and forming the mixed slurry to obtain a first sphere; step S3, covering the first sphere with the mixed slurry to perform second pelletizing forming to obtain a second sphere; step S4, heating and curing the second sphere to obtain a cured sphere; and step S5, condensing the solidified spheres to obtain the lightweight aggregate. The invention has the beneficial effects that: the method can directly utilize the dredged sludge produced by the dredging engineering by utilizing the used sludge, does not need dehydration treatment, does not have external drainage, greatly reduces energy consumption, simplifies the flow, reduces time and money, can treat large batch of dredged sludge at one time, and greatly reduces the possibility of secondary pollution. The aggregate has high strength and good waterproofness, so that the dredged sludge can be reused as a building material.
Description
Technical Field
The invention relates to the field of sludge resource utilization, in particular to a method for quickly preparing lightweight aggregate by utilizing dredged sludge.
Background
With the continuous promotion of the urbanization process in China, the sludge amount generated by dredging engineering in China is increased rapidly. The dredged sludge is difficult to be directly utilized in engineering due to the problems of high water content, low strength, long consolidation time and the like, and meanwhile, the dredged sludge contains a large amount of pollutants such as heavy metals and the like, so that the dredged sludge can cause difficult-to-repair damage to soil after being stacked for a long time and can cause harm to crops and human bodies, and therefore, the dredged sludge is not used as a natural organic fertilizer at present.
Most of the traditional disposal methods of the dredged sludge are a sludge throwing method and a stacking method, the sludge throwing method is divided into ocean sludge throwing and land sludge throwing, namely, the dredged sludge is conveyed into a specified sludge throwing area of an ocean and directly dumped into the ocean, the land sludge throwing is realized by directly discarding the dredged sludge in a low-lying area along a river or a lake, and the two methods can cause great pollution to the ocean and soil. The landfill method uses the dredged sludge as a filling material, but because the foundation soil formed by the method has low strength, a great deal of time and money are invested to treat the foundation in the later period, the development period is long, the operation is complex, secondary pollution is easy to generate, and the amount of sludge capable of being treated is limited. Later, people think of resource utilization of the dredging sludge, a mechanical dehydration method is usually adopted, particularly a plate-and-frame filter press is adopted to dehydrate the dredging sludge and solidify the dewatered sludge, the method is long in time consumption and can generate secondary pollution, and the method for manufacturing the lightweight aggregate by sintering the dredging sludge is one of the most common methods, but has the problems of huge energy consumption and large pollution.
Disclosure of Invention
In order to solve the technical problems, the invention provides a method for quickly preparing lightweight aggregate by using dredged sludge.
The specific technical scheme is as follows:
the method for quickly preparing the lightweight aggregate by using the dredged sludge is characterized by comprising the following steps of:
step S1, mixing the dredged sludge raw material with a homogenizing agent to obtain mixed slurry;
s2, pelletizing and forming the mixed slurry to obtain a first sphere;
step S3, covering the first sphere with the mixed slurry to perform second pelletizing forming to obtain a second sphere;
step S4, heating and curing the second sphere to obtain a cured sphere;
and step S5, condensing the solidified spheres to obtain the lightweight aggregate.
Further, in the step S1, the leveling agent accounts for 20% to 25% by mass of the mixed slurry.
Further, in the step S2, the diameter of the first sphere is smaller than 10 mm.
Further, in the step S3, the diameter of the second sphere is 15mm to 20 mm.
Further, in the step S4, the heating and curing are divided into preheating and steam heating, and the steam temperature is 80 to 150 ℃.
Further, in the step S5, the condensation time is 12 hours, and the condensation temperature is 20 to 22 ℃.
Further, the homogenizing agent includes bentonite and a beta-naphthalenesulfonic acid formaldehyde condensate.
Further, the step S4 is implemented in a heating system, the heating system includes a preheating device and a steam heating device, and the steam temperature is 80-150 ℃.
Further, the preheating device comprises a transverse preheating pipeline and a heating element arranged in the preheating pipeline; the steam heating device comprises a steam pipeline which is arranged below the preheating pipeline and is inclined, the steam pipeline is provided with a steam inlet, a ball inlet and a steam outlet, the ball inlet is aligned with the outlet of the preheating pipeline, and the steam outlet is arranged at one end, close to the preheating pipeline, of the steam pipeline and faces downwards.
Compared with the prior art, the invention has the beneficial effects that: (1) the method can directly utilize the dredged sludge produced by the dredging engineering by utilizing the used sludge, does not need dehydration treatment, does not have external drainage, greatly reduces energy consumption, simplifies the flow, reduces time and money, can treat large batch of dredged sludge at one time, and greatly reduces the possibility of secondary pollution. (2) The invention carries out balling and secondary coating on the sludge, utilizes steam heating and condensation for 12 hours, and can produce high-performance lightweight aggregate which has high strength. (3) The invention carries out secondary coating on the sludge, improves the strength and the waterproofness of the sludge, and enables the dredged sludge to be reused as building materials. (4) The preparation method is simple and efficient, and has strong popularization.
Drawings
FIG. 1 is a process flow diagram of the present invention;
FIG. 2 is a schematic diagram of a heating system;
the system comprises a preheating device-1, a preheating pipeline-101, a steam heating device-2, a steam pipeline-201, a steam inlet-2011, a ball inlet-2012, a steam outlet-2013 and a conveyor belt-3.
Detailed Description
The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.
Example one
Step S1, conveying dredged sludge to a slurrying pool through a conveyor belt, adding a homogenizing agent into the slurrying pool from the upper part, and fully and uniformly mixing the sludge and the slurrying agent in the slurrying pool to obtain mixed slurry; the slurrying tank is cylindrical, and the mixture in the slurrying tank does not settle more than 1% within four hours. The mass percentage of the solidification stabilizer in the mixed slurry is 20%.
And step S2, sending the uniformly mixed sludge into a granulator from the slurrying tank, and manufacturing spherical cores in a slurry spraying mode to form spherical cores of 5-10mm to obtain first spheres.
And step S3, finishing the wrapping and balling processes of the first spheres with qualified particle size, new sludge and medicament in a balling machine by using a guniting process to form second spheres with particle size of 15-20 mm, and finishing secondary wrapping.
Step S4, heating and curing the second spheres in sequence to obtain cured spheres; the heating and curing are divided into preheating and steam heating, and the steam temperature is 80-150 ℃.
And step S5, condensing the spheres for 12 hours through a transmission belt, wherein the condensation temperature is 20-22 ℃, and the lightweight aggregate is obtained.
Example two
Step S1, conveying dredged sludge to a slurrying pool through a conveyor belt, adding a homogenizing agent into the slurrying pool from the upper part, and fully and uniformly mixing the sludge and the homogenizing agent in the slurrying pool to obtain mixed slurry; the slurrying tank is cylindrical, and the mixture in the slurrying tank does not settle more than 1% within four hours. The mass percentage of the solidification stabilizer in the mixed slurry is 23%.
And step S2, sending the uniformly mixed sludge into a granulator from the slurrying tank, and manufacturing spherical cores in a slurry spraying mode to form spherical cores of 5-10mm to obtain first spheres.
And step S3, finishing the wrapping and balling processes of the first spheres with qualified particle size, new sludge and medicament in a balling machine by using a guniting process to form second spheres with particle size of 15-20 mm, and finishing secondary wrapping.
Step S4, heating and curing the second spheres in sequence to obtain cured spheres; the heating and curing are divided into preheating and steam heating, and the steam temperature is 80-150 ℃.
And step S5, condensing the spheres for 12 hours by a transmission belt, wherein the condensation temperature is 20-22 ℃.
Obtaining the lightweight aggregate.
EXAMPLE III
Step S1, conveying dredged sludge to a slurrying pool through a conveyor belt, adding a homogenizing agent into the slurrying pool from the upper part, and fully and uniformly mixing the sludge and the homogenizing agent in the slurrying pool to obtain mixed slurry; the slurrying tank is cylindrical, and the mixture in the slurrying tank does not settle more than 1% within four hours. The mass percentage of the solidification stabilizer in the mixed slurry is 25%.
And step S2, sending the uniformly mixed sludge into a granulator from the slurrying tank, and manufacturing spherical cores in a slurry spraying mode to form spherical cores of 5-10mm to obtain first spheres.
And step S3, finishing the wrapping and balling processes of the first spheres with qualified particle size, new sludge and medicament in a balling machine by using a guniting process to form second spheres with particle size of 15-20 mm, and finishing secondary wrapping.
Step S4, heating and curing the second spheres in sequence to obtain cured spheres; the heating and curing are divided into preheating and steam heating, and the steam temperature is 80-150 ℃.
And step S5, condensing the spheres for 12 hours through a transmission belt, wherein the condensation temperature is 20-22 ℃, and the lightweight aggregate is obtained.
In the first and third embodiments, the homogenizing agent includes bentonite and a β -naphthalenesulfonic acid formaldehyde condensate.
Example one to three steps S4 were performed in the following heating system:
the heating system comprises a preheating device 1 and a steam heating device 2. The preheating device 1 comprises a transverse preheating pipeline 101 and a heating element arranged in the preheating pipeline; the steam heating device 2 comprises a steam pipeline 201 which is arranged below the preheating pipeline 101 and is inclined, the steam pipeline 201 is provided with a steam inlet 2011, a ball inlet 2012 and a steam outlet 2013, the ball inlet 2012 is aligned with the outlet of the preheating pipeline 101, and the steam outlet 2013 is arranged at one end of the steam pipeline close to the preheating pipeline 101 and faces downwards.
And preheating the second sphere in a preheating pipeline when the second sphere enters the steam pipeline, wherein the steam is sprayed out from the lower oblique part to assist the second sphere to be sprayed out from an outlet at the upper oblique part, so that a solidified sphere is obtained.
Example four
Lightweight aggregate testing
The composite sphere can be dropped onto the steel plate at the height of 60 cm from the first to the third examples, so that the composite sphere does not crack 6 times, namely the composite sphere is qualified, and the detection results are shown in table 1.
TABLE 2 percent of pass of lightweight aggregate
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (9)
1. The method for quickly preparing the lightweight aggregate by using the dredged sludge is characterized by comprising the following steps of:
step S1, mixing the dredged sludge raw material with a homogenizing agent to obtain mixed slurry;
s2, pelletizing and forming the mixed slurry to obtain a first sphere;
step S3, covering the first sphere with the mixed slurry to perform second pelletizing forming to obtain a second sphere;
step S4, heating and curing the second sphere to obtain a cured sphere;
and step S5, condensing the solidified spheres to obtain the lightweight aggregate.
2. The method for rapidly preparing lightweight aggregate by using dredged sludge according to claim 1, wherein the homogenizing agent accounts for 20-25% of the mixed slurry in the step S1.
3. The method for rapidly preparing lightweight aggregate using dredged sludge as claimed in claim 1, wherein the diameter of the first sphere is less than 10mm in the step S2.
4. The method for rapidly preparing lightweight aggregate using dredged sludge as claimed in claim 1, wherein the diameter of the second sphere is 15mm to 20mm in the step S3.
5. The method for rapidly preparing lightweight aggregate using dredged sludge according to claim 1, wherein the heating and solidification are divided into preheating and steam heating at 80-150 ℃ in step S4.
6. The method for rapidly preparing lightweight aggregates by using dredged sludge according to claim 1, wherein the condensation time is 12 hours and the condensation temperature is 20 ℃ to 22 ℃ in the step S5.
7. The method for rapidly preparing lightweight aggregate using dredged sludge according to claim 1, wherein the homogenizing agent comprises bentonite and β -naphthalenesulfonic acid formaldehyde condensate.
8. The method for rapidly preparing lightweight aggregates using dredged sludge according to claim 1, wherein the step S4 is implemented in a heating system comprising a preheating device (1) and a steam heating device (2).
9. The method for the rapid preparation of lightweight aggregates using dredged sludge according to claim 8, characterized in that the preheating device (1) comprises a horizontal preheating pipe (101) and heating elements arranged inside the preheating pipe (101); steam heating device (2) are including locating preheat pipeline (101) below and steam conduit (201) of slope, steam conduit (201) are equipped with steam inlet (2011), spheroid entry (2012) and steam outlet (2013), spheroid entry (2012) with preheat pipeline (101) export and align, steam outlet (2013) are located steam conduit (201) are gone up and are close to preheat the one end of pipeline (101) and steam outlet is down.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911033679.3A CN110642544B (en) | 2019-10-28 | 2019-10-28 | Method for rapidly preparing lightweight aggregate by using dredged sludge |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911033679.3A CN110642544B (en) | 2019-10-28 | 2019-10-28 | Method for rapidly preparing lightweight aggregate by using dredged sludge |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110642544A true CN110642544A (en) | 2020-01-03 |
| CN110642544B CN110642544B (en) | 2022-01-28 |
Family
ID=69013663
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911033679.3A Active CN110642544B (en) | 2019-10-28 | 2019-10-28 | Method for rapidly preparing lightweight aggregate by using dredged sludge |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110642544B (en) |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001157899A (en) * | 1999-12-02 | 2001-06-12 | Hanshin Expressway Public Corp | Bottom mud treatment apparatus |
| TW565535B (en) * | 2000-06-16 | 2003-12-11 | Wen-Long Chyn | Sludge dredge handing and resource method and device |
| CN101066830A (en) * | 2007-05-18 | 2007-11-07 | 山东宏发重型机械有限公司 | Sludge-spraying drying process |
| CN102639452A (en) * | 2009-09-23 | 2012-08-15 | 凯努恩废物处理公司 | Method for drying sludge |
| CN105714104A (en) * | 2015-12-09 | 2016-06-29 | 涞源县奥宇钢铁有限公司 | Device for preheating to-be-sintered raw materials with steam and sludge |
| CN108178605A (en) * | 2018-01-05 | 2018-06-19 | 湖南省环境保护科学研究院(湖南省无公害生态经济研究所) | A kind of Preparation method and use of the residual mud baking-free ceramicite of high absorption property water supply plant |
| CN109650695A (en) * | 2018-12-25 | 2019-04-19 | 广东闻扬环境科技有限公司 | Sludge drying mechanism and drying method for sludge |
-
2019
- 2019-10-28 CN CN201911033679.3A patent/CN110642544B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001157899A (en) * | 1999-12-02 | 2001-06-12 | Hanshin Expressway Public Corp | Bottom mud treatment apparatus |
| TW565535B (en) * | 2000-06-16 | 2003-12-11 | Wen-Long Chyn | Sludge dredge handing and resource method and device |
| CN101066830A (en) * | 2007-05-18 | 2007-11-07 | 山东宏发重型机械有限公司 | Sludge-spraying drying process |
| CN102639452A (en) * | 2009-09-23 | 2012-08-15 | 凯努恩废物处理公司 | Method for drying sludge |
| CN105714104A (en) * | 2015-12-09 | 2016-06-29 | 涞源县奥宇钢铁有限公司 | Device for preheating to-be-sintered raw materials with steam and sludge |
| CN108178605A (en) * | 2018-01-05 | 2018-06-19 | 湖南省环境保护科学研究院(湖南省无公害生态经济研究所) | A kind of Preparation method and use of the residual mud baking-free ceramicite of high absorption property water supply plant |
| CN109650695A (en) * | 2018-12-25 | 2019-04-19 | 广东闻扬环境科技有限公司 | Sludge drying mechanism and drying method for sludge |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110642544B (en) | 2022-01-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107459364B (en) | High-strength ceramsite prepared by using yellow river sludge and sludge as binder and preparation method thereof | |
| CN105859068A (en) | Sludge treatment process | |
| CN110316936B (en) | Sea sludge recycling method and system | |
| CN101920520B (en) | Method for preparing gypsum building block with titanium gypsum | |
| CN103880464B (en) | Preparation process of concrete porous brick prepared from tubular pile residual slurry and waste incineration slag | |
| CN104261652B (en) | High-effective sludge dehydration flocculation agent | |
| CN104326634B (en) | A kind of compound sludge treatment technique | |
| CN102329147B (en) | Lightweight porcelain granule manufactured by utilizing printing and dyeing sludge and manufacturing method thereof | |
| CN111499138A (en) | Recycling treatment method for river sludge | |
| CN105776785A (en) | Diluting, conditioning and curing treatment method for sludge subjected to non-standardized treatment | |
| CN103170488A (en) | Waste incineration fly ash curing agent and treatment method of waste incineration fly ash | |
| CN108101511A (en) | A kind of heavy metal pollution earth cooperation flying ash prepares the microwave sintering method of haydite | |
| CN109679660A (en) | A kind of curing method of heavy-metal contaminated soil | |
| CN115041489B (en) | Harmless treatment method and device for electrolytic manganese slag by steam method | |
| CN107382113B (en) | High-strength recycled aggregate and production method thereof | |
| CN114956628A (en) | High-strength phosphogypsum-based recycled aggregate and preparation method thereof | |
| CN115582906A (en) | System and method for preparing carbon-fixing building material by using building decoration garbage recycled aggregate | |
| CN103965918A (en) | Curing agent for water quenching manganese slag mollisol | |
| CN107586003A (en) | Sludge treating agent and method for sludge treatment | |
| CN205443028U (en) | High dehydration rate device of bed mud | |
| CN110642544B (en) | Method for rapidly preparing lightweight aggregate by using dredged sludge | |
| CN106045420A (en) | Method for preparing foam sludge bricks from dredged sludge | |
| CN104045279B (en) | Utilize the method that residual slurry of tubular pile prepares novel light trench cover | |
| CN103910481A (en) | Method for carrying out curing treatment on landfill leachate membrane concentration solution sludge by using novel curing agent | |
| CN103936256A (en) | Method for mixing and drying sewage and sludge at normal temperature |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CB03 | Change of inventor or designer information | ||
| CB03 | Change of inventor or designer information |
Inventor after: Zhu Shujing Inventor after: Li Longfei Inventor after: Zhong Beibei Inventor after: Chen Xin Inventor after: Sun Yanhan Inventor after: Zhou Xingyue Inventor after: Tan Lin Inventor after: Fang Yuan Inventor after: Xie Shangru Inventor after: Hu Bei Inventor after: Xu Yulu Inventor after: Wen Hui Inventor before: Zhu Shujing Inventor before: Li Longfei Inventor before: Sun Yanhan Inventor before: Zhou Xingyue Inventor before: Tan Lin Inventor before: Fang Yuan Inventor before: Xie Shangru Inventor before: Hu Bei Inventor before: Xu Yulu Inventor before: Wen Hui |