A method for treating and circulating circulating water in a steel plant

Abstract

The present invention provides a water quality treatment and circulation method for circulating water in a steel plant, comprising the following steps: water point classification, water quality classification, desalted water preparation and post-use treatment, new water pre-use and post-use treatment, and turbid water pre-use and post-use treatment. The water-using equipment in the steel plant and the water quality requirements of the equipment are classified and graded, and desalted water, new water and turbid water are respectively supplied to corresponding water points according to the proportion of system water consumption, and corresponding water quality treatments are respectively performed before and after use, so as to meet the water quality requirements of the water points, protect the use safety and service life of the water-using equipment, reduce the loss of cooling or flushing water to equipment or products, and further realize the reuse of water resources and reduce enterprise sewage discharge through reasonable water circulation treatment.

Description

Technical Field

[0001] The present invention relates to a water treatment method, in particular to a water treatment and circulation method for circulating water in a steel plant, belonging to the technical field of steel smelting. Background Art

[0002] With economic development and the acceleration of industrialization, water resource issues have attracted considerable attention. The steel industry is particularly prominent in both fresh water consumption and wastewater discharge. The steel industry bears a significant responsibility for water conservation. Furthermore, the steel industry discharges significant amounts of wastewater, representing a significant proportion of total industrial wastewater discharge, and contains a significant amount of pollutants and hazardous substances. Therefore, to effectively treat steel industry wastewater, address water pollution, and fundamentally protect and conserve water resources, steelmaking and continuous casting projects are a core component of steelmaking operations. They connect the entire production chain, ensuring stable operations and crucially guaranteeing the inherent quality of the final product. Circulating water treatment stations for steelmaking and continuous casting are crucial supporting facilities for ensuring normal and stable steelmaking production.

[0003] At present, the water circulation in steel plants includes clean circulation and turbid circulation. The clean circulation is mainly for equipment cooling water, with low pollution level and simple water quality treatment. It can be put into use again after filtration and cooling. The turbid circulation is mainly used to wash waste slag generated in the steelmaking process. It does not have high requirements for water quality. The wastewater generated contains more impurities and the treatment process is complicated. In order to reduce the pressure of water quality treatment, some enterprises discharge the wastewater into the receiving water body after it meets the discharge standard. In the long run, the pollution of water bodies will become increasingly serious, polluting the environment and low water resource utilization rate. Summary of the Invention

[0004] Purpose of the invention: The present invention classifies and grades the water-using equipment and water quality requirements of the equipment in the steel plant, and supplies desalted water, new water and turbid water to the corresponding water use points according to the proportion of the system water consumption, and performs corresponding water quality treatment before and after use, so as to meet the water quality requirements of the water use points, protect the safety of use and service life of the water-using equipment, reduce the loss of cooling or flushing water to equipment or products, and further realize the reuse of water resources and reduce sewage discharge through reasonable water circulation treatment.

[0005] Technical solution: A method for treating and circulating circulating water in a steel mill, comprising the following steps:

[0006] S1: Water point classification: Steel mill water points are divided into primary water points, secondary water points and tertiary water points according to their water quality requirements;

[0007] S2: Water quality classification: Steel plant water quality is divided into demineralized water, new water and turbid water according to different water use points;

[0008] S3: Preparation of desalted water and post-use treatment: A desalination system and a desalted water tank are set up between the new water output end and the first-stage water point. The new water is filtered through the desalination equipment to obtain desalted water, which flows into the desalted water tank for storage and is pressurized by a pump to the first-stage water point;

[0009] After use, the primary water point is divided and pumped under pressure to the brine cooling tower and the new water channel between the new water pool and the clarifier;

[0010] S4: Treatment of new water before and after use: The new water tank, the clarifier tank and the self-cleaning filter are sequentially arranged between the new water output end and the secondary water point. The new water is filtered through the self-cleaning filter and then pressurized by a pump and flows into the secondary water point;

[0011] After use, the secondary water point is divided and pressurized by pumps to the new water channel between the new water pool and the clarifier and the tertiary water point;

[0012] S5: Turbid water treatment before and after use: A turbid water pool is set up between the secondary water point and the tertiary water point. The water from the secondary water point flows into the turbid water pool after use. At the same time, the supplementary water in the new pool is pumped under pressure to the turbid water pool;

[0013] The turbid water produced after the tertiary water use point is sent to the turbid water pool and the new water pool respectively after passing through the sewage treatment system.

[0014] Preferably, in S1:

[0015] The first-level water use point is an indirect cooling water use point, which mainly uses desalted water to cool the equipment; the second-level water use point is a direct cooling water use point, which mainly uses new water to cool the equipment; the third-level water use point is a flushing water use point, which mainly uses turbid water to flush and cool equipment and products.

[0016] Preferably, in S2:

[0017] The desalted water quality requirements are:

[0018] pH value 6.5~7.5

[0019] Suspended matter concentration / (mg·L -1 )≤1,

[0020] Ca hardness (CaCO3) / (mg·L -1 )≤0.5

[0021] Chloride ion mass concentration / (mg·L -1 )≤0.5

[0022] Conductivity / (μs·cm -1 )≤5

[0023] The new water quality requirements are:

[0024] pH value 7~8.5

[0025] Suspended matter concentration / (mg·L -1 )≤8,

[0026] Total hardness (CaCO3) / (mg·L -1 )≤190

[0027] Ca hardness (CaCO3) / (mg·L -1 )≤140

[0028] Chloride ion mass concentration / (mg·L -1 )≤90

[0029] Conductivity / (μs·cm -1 )≤550

[0030] Preferably, the S3 is specifically:

[0031] The method for obtaining desalted water is as follows: new water passes through a multi-media filter, an activated carbon filter, a water softener, a precision filter, a first-stage reverse osmosis, a pH adjustment, an intermediate water tank, a second-stage reverse osmosis, a purified water tank, a pure water pump and a microporous filter in sequence, and then the prepared desalted water is delivered to a first-stage water use point.

[0032] Preferably, after the first-level water point uses water, 75% to 80% of the desalted water is pressurized by a pump and sent into a desalted water cooling tower for cooling, and the cooled desalted water is sent to a desalted water pool; 20% to 25% of the desalted water is introduced into a new water channel and flows into the second-level water point as supplementary water.

[0033] Preferably, the S4 is specifically:

[0034] The treatment method for the new water entering the secondary water use point is to add a coagulant into the new water and let it enter the clarification tank for sedimentation, enter the self-cleaning filter to filter and flocculate the impurities into colloidal form, and finally enter the secondary water use point after disinfection.

[0035] Preferably, after the secondary water point uses water, 20% to 25% of the new water is pressurized by a pump and sent to the new water cooling tower for cooling. The cooled new water is sent to the new water stabilization tank, and after adding corrosion inhibitors and scale inhibitors and bactericides and algaecides, it is filtered and pressurized and sent to the new water channel; 75% to 80% of the new water is pressurized by a pump and sent to the tertiary water point.

[0036] Preferably, the S5 is specifically:

[0037] A turbid water filter tank is provided between the turbid water tank and the tertiary water use point, through which suspended particles and sediments are removed, and the filtered turbid water is then sent to the tertiary water use point.

[0038] Preferably, after the tertiary water use point uses water, the turbid water is sent to the sewage treatment system for primary filtration to remove suspended particles, sediment and water-insoluble oils in the water, and then 25%~30% of the turbid water after filtration is sent to the turbid water pool to enter the tertiary water use point again; 70%~75% of the turbid water is sent to the deep sewage treatment system for deep filtration to remove water-soluble oils, eliminate bacteria, purify residues, remove metal ions and odors, and the treated turbid water is sent to a new pool for recycling.

[0039] Beneficial effects:

[0040] The present invention classifies and grades the water-using equipment and water quality requirements of the equipment in the steel plant, and supplies desalted water, new water and turbid water to corresponding water use points according to the proportion of system water consumption, and performs corresponding water quality treatment before and after use, so as to meet the water quality requirements of the water use points, protect the safety of use and service life of the water-using equipment, reduce the loss of cooling or flushing water to equipment or products, and further realize the reuse of water resources and reduce enterprise sewage discharge through reasonable water circulation treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0042] Figure 1 This is a diagram of the water treatment and use steps of the present invention.

[0043] Figure 2 This is a diagram of the water treatment and diversion steps of the present invention. DETAILED DESCRIPTION

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0045] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0046] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0047] like Figure 1 and 2 As shown, a method for treating and circulating circulating water in a steel plant comprises the following steps:

[0048] S1: Water point classification: Steel mill water points are divided into primary water points, secondary water points and tertiary water points according to their water quality requirements;

[0049] Specifically: the first-level water use point is an indirect cooling water use point, which mainly uses desalted water to cool the equipment; the second-level water use point is a direct cooling water use point, which mainly uses new water to cool the equipment; the third-level water use point is a flushing water use point, which mainly uses turbid water to flush and cool equipment and products.

[0050] S2: Water quality classification: Steel plant water quality is divided into demineralized water, new water and turbid water according to different water use points;

[0051] The desalted water quality requirements are:

[0052] pH value 6.5~7.5

[0053] Suspended matter concentration / (mg·L -1 )≤1,

[0054] Ca hardness (CaCO3) / (mg·L -1 )≤0.5

[0055] Chloride ion mass concentration / (mg·L -1 )≤0.5

[0056] Conductivity / (μs·cm -1 )≤5

[0057] The new water quality requirements are:

[0058] pH value 7~8.5

[0059] Suspended matter concentration / (mg·L -1 )≤8,

[0060] Total hardness (CaCO3) / (mg·L -1 )≤190

[0061] Ca hardness (CaCO3) / (mg·L -1 )≤140

[0062] Chloride ion mass concentration / (mg·L -1 )≤90

[0063] Conductivity / (μs·cm -1 )≤550

[0064] S3: Preparation of desalted water and post-use treatment: A desalination system and a desalted water tank are set up between the new water output end and the first-stage water point. The new water is filtered through the desalination equipment to obtain desalted water, which flows into the desalted water tank for storage and is pressurized by a pump to the first-stage water point;

[0065] The method for obtaining desalted water is as follows: new water passes through a multi-media filter, an activated carbon filter, a water softener, a precision filter, a first-stage reverse osmosis, a pH adjustment, an intermediate water tank, a second-stage reverse osmosis, a purified water tank, a pure water pump and a microporous filter in sequence, and then the prepared desalted water is delivered to a first-stage water use point.

[0066] After the first-level water point uses water, 75% to 80% of the desalted water is pressurized by a pump and sent to the desalted water cooling tower for cooling, and the cooled desalted water is sent to the desalted water pool; 20% to 25% of the desalted water is introduced into the new water channel and flows into the second-level water point as supplementary water.

[0067] After use, the primary water point is divided and pumped under pressure to the brine cooling tower and the new water channel between the new water pool and the clarifier;

[0068] S4: Treatment of new water before and after use: a new water tank and a self-cleaning filter are set between the new water output end and the secondary water point. The new water is filtered by the self-cleaning filter and then pressurized by a pump and flows into the secondary water point;

[0069] After use, the secondary water point is divided and pressurized by pumps to the new water channel between the new water pool and the clarifier and the tertiary water point;

[0070] Specifically, the new water is treated by adding a coagulant into the new water, which enters a clarification tank for sedimentation, enters a self-cleaning filter to filter and flocculate into colloidal impurities, and finally enters the secondary water point after disinfection.

[0071] At the secondary water use point, after water is used, 20% to 25% of the new water is pressurized by a pump and sent to the new water cooling tower for cooling. The cooled new water is sent to the new water stabilization tank, and after adding corrosion inhibitors, scale inhibitors and bactericides, algaecides, it is filtered and pressurized and sent to the new water channel; 75% to 80% of the new water is pressurized by a pump and sent to the tertiary water use point.

[0072] S5: Turbid water treatment before and after use: A turbid water pool is set up between the secondary water point and the tertiary water point. The water from the secondary water point flows into the turbid water pool after use. At the same time, the supplementary water in the new pool is pumped under pressure to the turbid water pool;

[0073] The turbid water produced after the tertiary water use point is sent to the turbid water pool and the new water pool respectively after passing through the sewage treatment system.

[0074] Specifically, a turbid water filter pool is set between the turbid water pool and the tertiary water use point, and the suspended particles and sediments are removed through the turbid water filter pool, and then the filtered turbid water is sent to the tertiary water use point.

[0075] After the tertiary water use point uses water, the turbid water is sent to the sewage treatment system for primary filtration to remove suspended particles, sediment and water-insoluble oils in the water. Subsequently, 25% to 30% of the turbid water after filtration is sent to the turbid water pool to enter the tertiary water use point again; 70% to 75% of the turbid water is sent to the deep sewage treatment system for deep filtration to remove water-soluble oils, eliminate bacteria, purify residues, remove metal ions and odors, and the treated turbid water is sent to a new pool for recycling.

[0076] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0077] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for treating and circulating circulating water in a steel plant, characterized in that: The following steps are involved: S1: Water point classification: Steel mill water points are divided into primary water points, secondary water points and tertiary water points according to their water quality requirements; S2: Water quality classification: Steel plant water quality is divided into demineralized water, new water and turbid water according to different water use points; S3: Preparation of desalted water and post-use treatment: A desalination system and a desalted water tank are set up between the new water output end and the first-stage water point. The new water is filtered through the desalination equipment to obtain desalted water, which flows into the desalted water tank for storage and is pressurized by a pump to the first-stage water point; After use, the primary water point is divided and pumped under pressure to the brine cooling tower and the new water channel between the new water pool and the clarifier; S4: Treatment of new water before and after use: The new water tank, the clarifier tank and the self-cleaning filter are sequentially arranged between the new water output end and the secondary water point. The new water is filtered through the self-cleaning filter and then pressurized by a pump and flows into the secondary water point; After use, the secondary water point is divided and pressurized by pumps to the new water channel between the new water pool and the clarifier and the tertiary water point; S5: Turbid water treatment before and after use: A turbid water pool is set up between the secondary water point and the tertiary water point. The water from the secondary water point flows into the turbid water pool after use. At the same time, the supplementary water in the new pool is pumped under pressure to the turbid water pool; The turbid water generated after the tertiary water points are used is sent to the turbid water tank and the new water tank respectively after passing through the sewage treatment system; The S3 is specifically: The method for obtaining desalted water is as follows: new water passes through a multi-media filter, an activated carbon filter, a water softener, a precision filter, a first-stage reverse osmosis, a pH adjustment, an intermediate water tank, a second-stage reverse osmosis, a purified water tank, a pure water pump and a microporous filter in sequence, and then the prepared desalted water is delivered to a first-stage water point; After the primary water point uses water, 75% to 80% of the desalted water is pressurized by a pump and sent to the desalted water cooling tower for cooling, and the cooled desalted water is sent to the desalted water pool; 20% to 25% of the desalted water is introduced into the new water channel between the new water pool and the clarifier, and flows into the secondary water point as supplementary water; The S4 is specifically: The treatment method for the new water entering the secondary water point is as follows: after adding a coagulant into the new water, it enters a clarifier for sedimentation, enters a self-cleaning filter to filter and flocculate the impurities into a colloidal state, and finally enters the secondary water point after disinfection; After the secondary water point uses water, 20% to 25% of the new water is pressurized by a pump and sent to the new water cooling tower for cooling. The cooled new water is sent to the new water stabilization tank, and after adding corrosion inhibitors, scale inhibitors and bactericides and algaecides, it is filtered and pressurized and sent to the new water channel between the new water tank and the clarification tank; 75% to 80% of the new water is pressurized by a pump and sent to the tertiary water point; The S5 is specifically: After the tertiary water use point uses water, the turbid water is sent to the sewage treatment system for primary filtration to remove suspended particles, sediment and water-insoluble oils in the water. Then, 25% to 30% of the turbid water is sent to the turbid water pool and enters the tertiary water use point again; 70% to 75% of the turbid water is sent to the deep sewage treatment system for deep filtration to remove water-soluble oils, eliminate bacteria, purify residues, remove metal ions and odors, and the treated turbid water is sent to a new pool for recycling.

2. The method for treating and circulating circulating water in a steel plant according to claim 1, characterized in that: In S1: The first-level water point is an indirect cooling water point; the second-level water point is a direct cooling water point; and the third-level water point is a flushing water point.

3. The method for treating and circulating circulating water in a steel plant according to claim 1, wherein: In S2: The desalted water quality requirements are: pH value 6.5~7.5 Suspended matter concentration / (mg·L -1 )≤1, Ca hardness (CaCO3) / (mg·L -1 )≤0.5 Chloride ion mass concentration / (mg·L -1 )≤0.5 Conductivity / (μs·cm -1 )≤5 The new water quality requirements are: pH value 7~8.5 Suspended matter concentration / (mg·L -1 )≤8, Total hardness (CaCO3) / (mg·L -1 )≤190 Ca hardness (CaCO3) / (mg·L -1 )≤140 Chloride ion mass concentration / (mg·L -1 )≤90 Conductivity / (μs·cm -1 )≤550 4. The method for treating and circulating circulating water in a steel plant according to claim 1, wherein: The S5 is specifically: A turbid water filter tank is provided between the turbid water tank and the tertiary water use point, through which suspended particles and sediments are removed, and the filtered turbid water is then sent to the tertiary water use point.

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