CN116375154A - Treatment process of limestone washing wastewater - Google Patents
Treatment process of limestone washing wastewater Download PDFInfo
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- CN116375154A CN116375154A CN202310348182.0A CN202310348182A CN116375154A CN 116375154 A CN116375154 A CN 116375154A CN 202310348182 A CN202310348182 A CN 202310348182A CN 116375154 A CN116375154 A CN 116375154A
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- 235000019738 Limestone Nutrition 0.000 title claims abstract description 85
- 239000006028 limestone Substances 0.000 title claims abstract description 85
- 238000005406 washing Methods 0.000 title claims abstract description 76
- 239000002351 wastewater Substances 0.000 title claims abstract description 63
- 238000000034 method Methods 0.000 title claims abstract description 37
- 230000008569 process Effects 0.000 title claims abstract description 35
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 91
- 239000010802 sludge Substances 0.000 claims abstract description 51
- 238000005245 sintering Methods 0.000 claims abstract description 23
- 238000003756 stirring Methods 0.000 claims abstract description 18
- 238000005345 coagulation Methods 0.000 claims abstract description 17
- 230000015271 coagulation Effects 0.000 claims abstract description 17
- 238000004064 recycling Methods 0.000 claims abstract description 13
- 238000003860 storage Methods 0.000 claims abstract description 9
- 238000001035 drying Methods 0.000 claims abstract description 8
- 238000001556 precipitation Methods 0.000 claims abstract description 8
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 6
- 230000001376 precipitating effect Effects 0.000 claims abstract description 3
- 239000011780 sodium chloride Substances 0.000 claims abstract description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 14
- 238000004062 sedimentation Methods 0.000 claims description 13
- 239000002245 particle Substances 0.000 claims description 12
- 238000000926 separation method Methods 0.000 claims description 12
- 239000007864 aqueous solution Substances 0.000 claims description 10
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 4
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 4
- 239000000292 calcium oxide Substances 0.000 claims description 4
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 4
- 239000000395 magnesium oxide Substances 0.000 claims description 4
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 4
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 4
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 4
- 239000000377 silicon dioxide Substances 0.000 claims description 4
- 235000012239 silicon dioxide Nutrition 0.000 claims description 4
- 239000011593 sulfur Substances 0.000 claims description 4
- 229910052717 sulfur Inorganic materials 0.000 claims description 4
- 238000004065 wastewater treatment Methods 0.000 abstract description 12
- 238000005189 flocculation Methods 0.000 abstract description 7
- 239000010865 sewage Substances 0.000 description 13
- 239000000843 powder Substances 0.000 description 9
- 238000004140 cleaning Methods 0.000 description 8
- 238000012360 testing method Methods 0.000 description 8
- 230000006872 improvement Effects 0.000 description 7
- 238000005086 pumping Methods 0.000 description 7
- 239000002918 waste heat Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 239000004576 sand Substances 0.000 description 6
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 5
- 229940037003 alum Drugs 0.000 description 5
- 239000004568 cement Substances 0.000 description 5
- 239000003546 flue gas Substances 0.000 description 5
- 239000004615 ingredient Substances 0.000 description 5
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 4
- 235000011941 Tilia x europaea Nutrition 0.000 description 4
- 230000016615 flocculation Effects 0.000 description 4
- 239000004571 lime Substances 0.000 description 4
- 238000001179 sorption measurement Methods 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 239000012535 impurity Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000009628 steelmaking Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- 238000005299 abrasion Methods 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000002689 soil Substances 0.000 description 2
- 239000004575 stone Substances 0.000 description 2
- 239000002671 adjuvant Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 238000000643 oven drying Methods 0.000 description 1
- JTJMJGYZQZDUJJ-UHFFFAOYSA-N phencyclidine Chemical class C1CCCCN1C1(C=2C=CC=CC=2)CCCCC1 JTJMJGYZQZDUJJ-UHFFFAOYSA-N 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
- C02F1/56—Macromolecular compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/121—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering
- C02F11/127—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering by centrifugation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/13—Treatment of sludge; Devices therefor by de-watering, drying or thickening by heating
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F2001/007—Processes including a sedimentation step
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Inorganic Chemistry (AREA)
- Separation Of Suspended Particles By Flocculating Agents (AREA)
- Treatment Of Sludge (AREA)
Abstract
The invention discloses a treatment process of limestone washing wastewater, and belongs to the field of wastewater treatment. It comprises the following steps: 1. adding limestone washing wastewater into a coagulation tank, adding PAC (sodium chloride) and fully stirring, and then adding PAM and fully stirring; 2. adding the wastewater treated in the first step into a precipitation tank, fully stirring, precipitating until mud water is layered, and then transporting clear water to storage equipment through a pipeline to leave sludge; 3. conveying the sludge to a dryer for drying; 4. and conveying the dried sludge to a sintering bin for standby. According to the characteristics of the limestone washing wastewater, the invention adopts a specially designed dosing flocculation process, and can finish the efficient treatment of the limestone washing wastewater without large facilities, thereby realizing the efficient recycling utilization of limestone.
Description
Technical Field
The invention belongs to the field of wastewater treatment, and particularly relates to a limestone water-washing wastewater treatment process.
Background
Lime is one of the important steelmaking adjuvants in the daily production of steelworks, the quality of which can directly affect the quality of the final product of steelmaking. However, the limestone inevitably entrains some impurities during the mining process, and if the impurities are not removed, the quality of lime is affected, so that the quality of steel-making products is further affected. At present, the domestic lime kiln mostly adopts a water washing mode to remove surface impurities carried by limestone before production so as to improve the quality of limestone raw materials and ensure the quality of lime, and a large amount of wastewater generated in the water washing process of limestone is discharged directly without treatment, so that the wastewater can cause great pollution to the environment. Meanwhile, the sludge in the part of wastewater can be reused if treated, so that the resource utilization efficiency of a steel mill is improved.
At present, most of the prior art adopts a sedimentation tank and a concentration tank process for treating the wastewater, however, the process not only occupies a large area and has low treatment efficiency, but also generates limestone water-washing sludge with the water content of more than 30 percent, which has large viscosity and is difficult to dewater, thereby causing difficulty in recycling the limestone water-washing sludge.
The Chinese patent application number is: CN201911029177.3, publication date: patent literature on 2 month and 4 days in 2020 discloses a water washing manufacturing grading process for building and industrial aggregates, which is characterized in that the scheme is used for washing to remove stone powder, soil and other harmful components which affect the quality of concrete and are entrained in aggregates such as limestone or machine-made sand, the stone powder and the soil entrained in the aggregates are manufactured into mud cakes for use, sewage generated by water washing of the aggregates overflows from a spiral sand washer, the sewage is led into a first-stage sedimentation tank of a screening workshop, four fine sand recycling cyclones are arranged in the first-stage sedimentation tank, small particles which cannot be washed by the sand washer are recycled again, and the fine sand enters a water washing sand finished product warehouse through a sealing belt conveyor after being dehydrated through a dewatering screen, so that the sewage is recycled, and the environment-friendly, economical, efficient and reasonable aggregate processing and manufacturing are realized.
The Chinese patent application number is: CN202022714593.1, publication date: 2021, 7 months and 2 days, discloses a limestone water washing system, which comprises a feed inlet and a cleaning machine connected with the feed inlet through a conveyor belt, wherein a spiral shaft and a spiral blade fixed on the spiral shaft are arranged in the cleaning machine, a sewage treatment system is arranged below the cleaning machine, the sewage treatment system comprises a sedimentation tank, a transition tank, a clean water tank and an automatic chemical feeder, a water circulation system is arranged above the cleaning machine, and wear-resistant coatings are arranged on the spiral shaft and the spiral blade of the cleaning machine; and a filter assembly is arranged between the sedimentation tank and the transition tank and between the transition tank and the clean water tank, and a filter screen is arranged below the cleaning machine. The abrasion-resistant coating is sprayed on the spiral shaft and the spiral blade of the cleaning machine, so that the abrasion resistance of the spiral shaft and the spiral blade can be effectively improved, and further the economic loss caused by shutdown maintenance of the cleaning machine is reduced; through the setting of the filter component in the sewage treatment system, the sludge can be prevented from being deposited on the filter screen, the filter screen is blocked, and then the sewage treatment efficiency is improved.
In the two schemes, the treatment of the limestone washing wastewater is involved, however, the treatment of the wastewater is carried out by adopting a large facility such as a sedimentation tank, and although the technology of the sedimentation tank and the concentration tank is improved, the problems of longer treatment time, larger occupied area of facilities and the like caused by the existence of large-scale equipment such as the sedimentation tank and the like inevitably exist, thereby greatly influencing the whole production of a steel mill.
Disclosure of Invention
1. Problems to be solved
Aiming at the problems of longer sewage treatment time and larger occupied area of facilities in the existing limestone washing wastewater treatment process, the invention provides the limestone washing wastewater treatment process which can finish the efficient treatment of the limestone washing wastewater without large facilities, thereby realizing the efficient recycling utilization of limestone.
2. Technical proposal
In order to solve the problems, the invention adopts the following technical scheme.
A limestone water washing wastewater treatment process comprises the following steps:
1. adding limestone washing wastewater into a coagulation tank, adding PAC (sodium chloride) and fully stirring, and then adding PAM and fully stirring;
2. adding the wastewater treated in the first step into a precipitation tank, fully stirring, precipitating until mud water is layered, and then transporting clear water to storage equipment through a pipeline to leave sludge;
3. conveying the sludge to a dryer for drying;
4. and conveying the dried sludge to a sintering bin for standby.
As a further improvement of the technical scheme, the second step further includes: and conveying the layered sludge to a centrifugal sludge-water separator for further sludge-water separation, and conveying clear water to water storage equipment through a pipeline.
In the second step, the separated clean water is returned to the water storage equipment of the limestone washing system through a pipeline for recycling.
As a further improvement of the technical scheme, in the first step, every 1m 3 0.1-0.5 kg PAC is added into the limestone washing wastewater, and the limestone washing wastewater is prepared into 10-30% aqueous solution for use.
As a further improvement of the technical scheme, in the first step, every 1m 3 0.003-0.005 kg of PAM is added into the limestone washing wastewater, and the limestone washing wastewater is prepared into 0.1-0.3% aqueous solution for use.
In the second step, the mud water in the precipitation tank is layered and then the mud water exists in clear water in a granular form, and the mass ratio of the mud water is (15% -30%): (70% -85%).
As a further improvement of the technical scheme, in the first step, PAC is added and stirred for 1-5 min, and PAM is added and stirred for 0.5-2 min.
As a further improvement of the technical scheme, in the second step, the content of suspended matters in the obtained clean water is lower than 30mg/L.
As a further improvement of the technical scheme, in the first step and the second step, the coagulation tank and the sedimentation tank are respectively provided with an electric stirrer.
As a further improvement of the technical scheme, in the step three, the water content of the dried sludge is 8% -15%, the particle content of the dried sludge with the granularity larger than 5mm is less than or equal to 1%, the calcium oxide content is more than or equal to 52%, the silicon dioxide content is less than 1.8%, the magnesium oxide content is less than 0.6%, the aluminum oxide content is less than 0.8% and the sulfur content is less than 0.1%.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) According to the characteristics of the limestone washing wastewater, the quick cement separation of the limestone washing wastewater is realized by adopting a specially designed dosing flocculation process, namely PAC is firstly added to enable suspended particles with extremely small particle diameters in the wastewater to be mutually combined and become large through the effects of surface adsorption, van der Waals attraction and the like, so that relatively large alum flowers are formed, the suspended particles are separated from the wastewater to achieve the coagulation effect, PAM is further added, and the alum flowers are further enlarged through the effects of adsorption bridging, flocculation, net capturing and the like, so that sedimentation and quick flocculation are accelerated, and mud water quick separation is realized;
(2) According to the limestone washing wastewater treatment process, on the basis of realizing rapid cement separation of the limestone washing wastewater, the concentration of total suspended matters in separated clear water can be ensured to be lower than 30mg/L, so that the limestone washing wastewater treatment process can return to a limestone washing system for recycling, and the water resource utilization rate is improved;
(3) According to the limestone washing wastewater treatment process, the separated sludge is dehydrated in a centrifugal and low-temperature drying mode, the water content of the sludge after treatment is 8% -15%, the particle content of the sludge with the granularity of more than 5mm is less than or equal to 1%, the calcium oxide content is more than or equal to 52%, the silicon dioxide content is less than 1.8%, the magnesium oxide content is less than 0.6%, the aluminum oxide content is less than 0.8%, and the sulfur content is less than 0.1%, and the limestone powder is basically similar to the component parameters of the limestone powder used for sintering ingredients, so that the limestone powder can be completely replaced for sintering ingredients, the quality of sintered minerals is not influenced, and the recycling of 100% of sintering is realized.
Drawings
FIG. 1 is a flow chart of a treatment process of limestone washing wastewater.
Detailed Description
Exemplary embodiments of the present invention are described in detail below. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, it is to be understood that other embodiments may be realized and that various changes to the invention may be made without departing from the spirit and scope of the invention. The following more detailed description of the embodiments of the invention is not intended to limit the scope of the invention, as claimed, but is merely illustrative and not limiting of the invention's features and characteristics in order to set forth the best mode of carrying out the invention and to sufficiently enable those skilled in the art to practice the invention. Accordingly, the scope of the invention is limited only by the attached claims.
A process for treating the sewage generated by washing limestone features that when the water is washed by limestone, the sewage generated by washing is treated to prevent the environmental pollution caused by direct discharge of sewage from washing limestone and to recover the waste resources.
As shown in fig. 1, the treatment process of the limestone washing wastewater comprises the following steps:
1. adding limestone washing wastewater into a coagulation box, wherein an electric stirrer is arranged in the coagulation box, adding PAC through an automatic dosing device and fully stirring for 1-5 min, and then adding PAM and fully stirring for 0.5-2 min. In this step, every 1m 3 Adding 0.1-0.5 kg PAC into the limestone washing wastewater,and preparing 10% -30% aqueous solution for use; every 1m 3 0.003-0.005 kg of PAM is added into the limestone washing wastewater, and the limestone washing wastewater is prepared into 0.1-0.3% aqueous solution for use.
In the step, PAC is added to make suspended particles with extremely small particle size in the wastewater mutually combined and enlarged through the actions of surface adsorption, van der Waals attraction and the like, so that relatively large alum is formed, and the alum is separated from the wastewater, thereby achieving the coagulation effect. And then PAM is further added, so that alum blossom is further enlarged through the actions of adsorption bridging, flocculation, net capturing and the like of the PAM, sedimentation is quickened, and quick flocculation is realized, thereby being an extremely important foundation for realizing quick separation and identification of mud water for the subsequent process.
2. Adding the limestone washing wastewater treated in the first step into a settling tank in a self-retaining or pumping mode, wherein an electric stirrer is arranged in the settling tank, stirring for 0.5-1 min and then settling for 1-5 min to enable muddy water to be layered, and at the moment, the sludge in the settling tank exists in clear water in a granular form, wherein the mass ratio of the muddy water is (15% -30%): (70% -85%), then the clean water is conveyed to return to the water storage equipment of the limestone washing system through a pipeline for recycling.
And then, conveying the layered sludge to a centrifugal sludge-water separator for further sludge-water separation, and returning clear water to water storage equipment of a limestone washing system for recycling through a pipeline, wherein the water content of the remained sludge is 25% -35%.
In the step, the treatment of the water washing wastewater in the step one ensures that the concentration of total suspended matters in separated clear water is lower than 30mg/L on the basis of realizing the rapid cement separation of the limestone water washing wastewater, thereby returning to a limestone water washing system for recycling and improving the water resource utilization rate.
3. And conveying the residual sludge in the sludge-water separator to a dryer through sludge conveying equipment such as a screw conveyor and the like for drying, wherein the heat source of the dryer is waste heat flue gas or steam at 100-400 ℃ of a steelworks, such as sintering flue gas, coal-fired boiler flue gas, wind crushed steam, hot stuffy steel slag waste heat steam and the like.
The limestone washing wastewater treatment process has the advantages that the separated sludge is dehydrated in a centrifugal and low-temperature drying mode, so that waste heat resources of a steel mill are effectively utilized, the water content of the treated sludge is 8% -15%, the particle content of the treated sludge with the granularity of more than 5mm is less than or equal to 1%, the calcium oxide content is more than or equal to 52%, the silicon dioxide content is less than 1.8%, the magnesium oxide content is less than 0.6%, the aluminum oxide content is less than 0.8% and the sulfur content is less than 0.1%, the treated sludge is basically similar to the component parameters of the limestone powder used for sintering ingredients, the limestone powder can be completely replaced for sintering ingredients, the quality of sintering minerals is not influenced, and the recycling of 100% of sintering is realized.
4. And conveying the dried sludge to a sintering bunker for standby through a suction-discharge type tank car.
In summary, according to the limestone washing wastewater treatment process, according to the characteristics of the limestone washing wastewater, the quick cement separation of the limestone washing wastewater is realized by adopting the specially designed dosing flocculation process, the process is simple, the treatment efficiency is high, the treatment process is green and environment-friendly, and no secondary pollution is generated. Meanwhile, the cement separation of the limestone washing wastewater can be quickly completed without long-time precipitation by adopting large-scale equipment of a sedimentation tank, and the wastewater treatment time and the equipment floor area are saved.
In order to further understand the technical effects of the treatment process of the present application, the implementation procedure and data in specific production experiments are given below.
Example 1
1. The limestone washing wastewater is conveyed to a coagulation tank by a sewage pump and is mixed according to the ratio of 0.1kg/m 3 Adding 15% PAC aqueous solution prepared from wastewater with dosage into a coagulation tank, stirring for 1min, and adding 0.003kg/m 3 Adding the PAM aqueous solution with the dosage of 0.2% prepared by the wastewater into a coagulation box, and stirring for 0.5min.
2. And (3) conveying the wastewater in the coagulation tank to the precipitation tank in a pumping mode, stirring for 1min, then staying for 3min, conveying clear water to a water return pipeline in a pumping mode after the muddy water is completely layered, and returning to a limestone washing system for use, wherein the total suspended matter content in the clear water is 17mg/L.
And then, conveying the precipitated sludge to a centrifugal sludge-water separator by adopting a sludge pump to further separate sludge from water, conveying clear water after separation to a return water pipeline in a pumping mode, and returning to a limestone washing system for utilization, wherein the total suspended matter content in the clear water is 22mg/L.
3. The sludge separated by the centrifugal mud-water separator is conveyed to a dryer by adopting a screw conveyor, the sludge is dried by adopting sintering waste heat flue gas, the temperature of the waste heat steam is 200 ℃, and the flow is 10Wm 3 And/h, wherein the drying time is 3h. The water content of the dried sludge is 10%.
4. And conveying the dried sludge to a sintering bunker for standby by adopting a suction-discharge type tank car.
Example 2
1. The limestone washing wastewater is conveyed to a coagulation tank by a sewage pump and is mixed according to the ratio of 0.15kg/m 3 Adding 20% PAC aqueous solution prepared from wastewater with dosage into a coagulation tank, stirring for 2min, and adding 0.005kg/m 3 Adding the PAM aqueous solution with the dosage of 0.1% prepared by the wastewater into a coagulation box, and stirring for 0.5min.
2. And (3) conveying the wastewater in the coagulation tank to the precipitation tank in a pumping mode, stirring for 0.5min, then staying for 4min, conveying clear water to a water return pipeline in a pumping mode after the muddy water is completely layered, and returning to a limestone washing system for use, wherein the total suspended matter content in the clear water is 20mg/L.
And then, conveying the precipitated sludge to a centrifugal sludge-water separator by adopting a sludge pump to further separate sludge from water, conveying clear water after separation to a return water pipeline in a pumping mode, and returning to a limestone washing system for utilization, wherein the total suspended matter content in the clear water is 23mg/L.
3. The sludge separated by the centrifugal mud-water separator is conveyed to a dryer by adopting a screw conveyor, the sludge is dried by adopting waste heat flue gas of a coal-fired boiler, the temperature of the waste heat steam is 260 ℃, and the flow is 10Wm 3 And/h, wherein the drying time is 2h. The water content of the dried sludge is 8%.
4. And conveying the dried sludge to a sintering bunker for standby by adopting a suction-discharge type tank car.
In the two examples, the particle size of the dried sludge is shown in the following table 1, and the chemical composition is shown in the following table 2.
TABLE 1 sludge particle size after oven drying, wt%
TABLE 2 sludge major chemical composition, wt%
The sintering properties of the dried sludge of examples 1 and 2 were verified by a sintering cup test, the test process parameters are shown in the following table 3, the sintering test proportions are shown in the following table 4, and the sintering test results are shown in the following table 5.
TABLE 3 main parameter table for sintered cup test
Table 4 test proportions of the fritted cup, wt%
TABLE 5 results of sintered cup test
It can be seen from table 5 that examples 1-2 are similar to the various test properties of the limestone powder of the reference group used in the prior art sintering formulations. Therefore, the dried limestone sludge can be used for sintering ingredients by replacing limestone powder by 100%, the quality of sintering ore is not affected, and 100% recycling of the limestone sludge in the sintering process is realized.
Claims (10)
1. A process for treating limestone washing wastewater is characterized by comprising the following steps of: the method comprises the following steps:
1. adding limestone washing wastewater into a coagulation tank, adding PAC (sodium chloride) and fully stirring, and then adding PAM and fully stirring;
2. adding the wastewater treated in the first step into a precipitation tank, fully stirring, precipitating until mud water is layered, and then transporting clear water to storage equipment through a pipeline to leave sludge;
3. conveying the sludge to a dryer for drying;
4. and conveying the dried sludge to a sintering bin for standby.
2. The process for treating limestone washing wastewater according to claim 1, wherein: the second step further comprises: and conveying the layered sludge to a centrifugal sludge-water separator for further sludge-water separation, and conveying clear water to water storage equipment through a pipeline.
3. The process for treating limestone washing wastewater according to claim 2, wherein: in the second step, the separated clean water is returned to the water storage equipment of the limestone washing system through a pipeline for recycling.
4. A process for treating limestone water washing wastewater according to claim 3 wherein: in the first step, every 1m 3 0.1-0.5 kg PAC is added into the limestone washing wastewater, and the limestone washing wastewater is prepared into 10-30% aqueous solution for use.
5. The process for treating limestone washing wastewater according to claim 4, wherein: in the first step, every 1m 3 0.003-0.005 kg of PAM is added into the limestone washing wastewater, and the limestone washing wastewater is prepared into 0.1-0.3% aqueous solution for use.
6. The process for treating limestone washing wastewater according to claim 5, wherein: in the second step, the mud and water in the precipitation tank are layered and then the mud and water exist in clear water in a granular form, and the mass ratio of the mud and water is (15% -30%): (70% -85%).
7. A process for treating limestone water washing wastewater according to any one of claims 1-6 wherein: in the first step, PAC is added and stirred for 1-5 min, and PAM is added and stirred for 0.5-2 min.
8. A process for treating limestone water washing wastewater according to any one of claims 1-6 wherein: in the second step, the content of suspended matters in the obtained clear water is lower than 30mg/L.
9. A process for treating limestone water washing wastewater according to any one of claims 1-6 wherein: in the first step and the second step, electric stirrers are arranged in the coagulation tank and the sedimentation tank.
10. A process for treating limestone water washing wastewater according to any one of claims 1-6 wherein: in the third step, the water content of the dried sludge is 8% -15%, the particle content with the granularity larger than 5mm is less than or equal to 1%, the calcium oxide content is more than or equal to 52%, the silicon dioxide content is less than 1.8%, the magnesium oxide content is less than 0.6%, the aluminum oxide content is less than 0.8% and the sulfur content is less than 0.1%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310348182.0A CN116375154A (en) | 2023-03-31 | 2023-03-31 | Treatment process of limestone washing wastewater |
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