A single-stage water washing desalting system and a filter cake quality control method thereof

Abstract

This invention provides a single-stage water washing desalination system and its filter cake quality control method. When the single-stage water washing desalination system is in a stable operating state, the alkali metal salt concentration of the clarified liquid produced by the solid-liquid separation device and the moisture content of the filter cake are obtained. The single-stage water washing desalination system includes a slurry tank and a solid-liquid separation device. The slurry tank receives fresh water and dust and produces a mixed slurry. The solid-liquid separation device receives the slurry and produces clarified liquid and filter cake. The alkali metal salt content of the filter cake is determined based on the alkali metal salt concentration of the clarified liquid and the moisture content of the filter cake. It is then determined whether the alkali metal salt content of the filter cake is less than the controlled alkali metal salt content. If the alkali metal salt content of the filter cake is less than the controlled alkali metal salt content, it is determined that the alkali metal in the filter cake will not accumulate in the sintering raw materials, and the filter cake is sent to the sintering batching process to participate in sintering. This application improves resource utilization by controlling the alkali metal content of the filter cake, allowing the filter cake to participate in sintering production as a raw material without causing alkali metal accumulation.

Description

Technical Field

[0001] This invention relates to the field of sintering dust disposal technology, and in particular to a single-stage water washing and desalination system and its filter cake quality control method. Background Technology

[0002] Sintering dust mainly comes from dust generated during the sintering machine head, tail, and environmental dust removal processes, especially the dust from the sintering machine head, which contains a relatively high amount of alkali metal elements such as K and Na.

[0003] Currently, the commonly used method is as follows: Figure 4 The typical water washing desalination system shown removes alkali metal elements such as K and Na. The working principle of the water washing desalination system is mainly based on two core processes: water washing and evaporation crystallization. The water washing process separates soluble substances (such as K and Na) from the dust, and the evaporation crystallization technology crystallizes and separates the salt in the washing liquid, producing by-product salt. The filter cake produced by the solid-liquid separation device is used as sintering raw material and re-enters the sintering batching process to participate in the sintering process again, realizing the recycling of resources in the dust.

[0004] However, existing technologies typically employ the same water washing process for all dust collector ash, for example, washing all the dust from the electrostatic precipitator head according to... Figure 4 The multi-stage or single-stage washing process shown is problematic because the source and composition of dust from sintering plants are often uncertain. This leads to an indeterminate final washing solution concentration when using the same washing process. The water in the filter cake comes from the slurry, which is actually an alkali metal solution. Part of the water flows through the clear liquid channel, while the remainder flows with the filter cake. The alkali metal salts in the filter cake are brought in by the alkali metal solution that flows with the filter cake. Consequently, the alkali metal concentration in the filter cake may be higher or lower than that in the sintering raw materials. Since Fe in the dust is required for the sintering process, while alkali metals such as K and Na are not, if the content of alkali metals such as K and Na is higher than that in the sintering raw materials, the filter cake will re-enter the sintering process, leading to the enrichment of alkali metals in the raw materials. This is detrimental to subsequent sintering production and the quality of the sintered ore.

[0005] In view of this, it is necessary to propose a single-stage water washing desalination system and its filter cake quality control method to solve or at least alleviate the above-mentioned defects. Summary of the Invention

[0006] The main objective of this invention is to provide a single-stage water washing desalination system and its filter cake quality control method to solve the technical problem that, due to the uncertainty of the source or composition of dust from sintering plants, the alkali metal content of the filter cake is higher than that of the sintering raw materials. This leads to the filter cake re-entering the sintering process, resulting in the enrichment of alkali metals in the raw materials, which is detrimental to subsequent sintering production and the quality of sintered ore.

[0007] To achieve the above objectives, the present invention provides a method for filter cake quality control in a single-stage water washing desalination system, comprising the following steps:

[0008] S1, when the single-stage water washing desalination system is in a stable working state, the alkali metal salt concentration of the clear liquid produced by the solid-liquid separation device and the moisture content of the filter cake are obtained; wherein, the single-stage water washing desalination system includes a slurry tank and a solid-liquid separation device, the slurry tank receives fresh water and dust and produces a mixed slurry, and the solid-liquid separation device is used to receive the slurry and produce clear liquid and filter cake;

[0009] S2, determine the alkali metal salt content of the filter cake based on the alkali metal salt concentration of the clarified liquid and the moisture content of the filter cake, and determine whether the alkali metal salt content of the filter cake is less than the alkali metal salt control content;

[0010] S3, when the alkali metal salt content of the filter cake is less than the alkali metal salt control content, it is determined that the alkali metal in the filter cake will not be enriched in the sintering raw materials, and the filter cake is sent to the sintering batching process to participate in sintering.

[0011] Preferably, step S2, determining the alkali metal salt content of the filter cake based on the alkali metal salt concentration of the clarified liquid and the moisture content of the filter cake, specifically includes the following steps: using a formula... Determine the alkali metal salt content of the filter cake; wherein, ND B1 The content of alkali metal salts in filter cake B1 is expressed in %, CM. B1 The amount of filter cake produced by the solid-liquid separation device, in kg, HS B1 ND represents the moisture content of filter cake B1, in % . G1 The concentration of the alkali metal salt in the supernatant G1 is expressed as %.

[0012] Preferably, obtaining the alkali metal salt concentration of the clarified liquid produced by the solid-liquid separation device in step S1 specifically includes the following steps: using the formula The concentration of alkali metal salts ND in the clarified liquid produced by the solid-liquid separation device was calculated. G1 Among them, LL B To ensure stable operation, the slurry tank requires the addition of dust collector ash at a flow rate of kg / s, ND. B The content of alkali metal salts in dust B, in %, LL AThe water flow rate added to the slurry tank during stable operation is expressed in kg / s; HS B The water content in dust B is expressed as a percentage.

[0013] Preferably, when the alkali metal salt content in the filter cake is greater than or equal to the controlled alkali metal salt content,

[0014] Using formula ND GK2 =k2 / HS B1 Determine the concentration of the clarified liquid (ND) that meets the alkali metal control requirements for the filter cake. GK2 The unit is %, and k2 is the control standard for alkali metal salt content in filter cake, in %;

[0015] Using formula Determine the water supply by adding water valve AF1; where LL AK2 For continuous production in the slurry tank, add water valve AF1 to control the flow rate, in units of kg / s;

[0016] Adjust the control flow of the water valve AF1 to LL. AK2 .

[0017] Preferably, the alkali metal salt content control standard k2 of the filter cake is obtained through the following steps:

[0018] Obtain the sintering raw material batching ratio for a future production cycle, and determine the alkali metal content J corresponding to the sintering raw material batching ratio, in %;

[0019] Using formula Determine the control standard k2 for the alkali metal salt content of the filter cake; where H is a correction coefficient considering engineering errors.

[0020] Preferably, the moisture content of the filter cake is between 20% and 30%.

[0021] Preferably, the correction factor H is set between 1.0 and 1.5.

[0022] This invention also provides a single-stage water washing and desalination system, including a slurry tank and a solid-liquid separation device. The slurry tank includes a slurry tank body, a water inlet assembly for receiving external fresh water, an ash inlet assembly for receiving dust, and a slurry outlet assembly. The water inlet assembly is equipped with a first water inlet valve, and the slurry outlet assembly is equipped with a slurry outlet valve. Water enters the slurry tank body through the water inlet assembly, and dust enters the slurry tank body through the ash inlet assembly. The water and dust mix in the slurry tank body to form a slurry. The solid-liquid separation device is used to receive the slurry from the slurry outlet assembly and produce a clear liquid and a filter cake.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] This invention provides a single-stage water washing desalination system and its filter cake quality control method. When the single-stage water washing desalination system is in a stable operating state, the alkali metal salt concentration of the clarified liquid produced by the solid-liquid separation device and the moisture content of the filter cake are obtained. The single-stage water washing desalination system includes a slurry tank and a solid-liquid separation device. The slurry tank receives fresh water and dust and produces a mixed slurry. The solid-liquid separation device receives the slurry and produces clarified liquid and filter cake. The alkali metal salt content of the filter cake is determined based on the alkali metal salt concentration of the clarified liquid and the moisture content of the filter cake. It is then determined whether the alkali metal salt content of the filter cake is less than the controlled alkali metal salt content. If the alkali metal salt content of the filter cake is less than the controlled alkali metal salt content, it is determined that the alkali metal in the filter cake will not accumulate in the sintering raw materials, and the filter cake is sent to the sintering batching process to participate in sintering. This application improves resource utilization by controlling the alkali metal content of the filter cake, allowing the filter cake to participate in sintering production as a raw material without causing alkali metal accumulation. Secondly, when the alkali metal salt content of the filter cake is greater than or equal to the controlled alkali metal salt content, this application adjusts the flow rate of the water addition valve AF1 in the slurry tank by adjusting the flow rate, so that the alkali metal salt content of the filter cake is reduced to the expected range. This allows the filter cake to be sent to the sintering batching process as a sintering raw material without causing alkali metal enrichment, and can quickly guide the flow rate control of the water addition valve, achieving accurate and rapid adjustment. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0026] Figure 1 This is a schematic flowchart of one embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of an electrostatic precipitator system for sintering machine heads in the prior art.

[0028] Figure 3 This is a schematic diagram of a typical ash removal sequence for a four-field electrostatic precipitator in an existing sintering machine head.

[0029] Figure 4 This is a flowchart of a typical water washing and desalination method in the prior art.

[0030] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0031] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0034] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0035] Those skilled in the art should know that with the rapid development of modern industry, the scale of steel production is increasing, and energy consumption is also increasing. Energy conservation and environmental protection indicators are becoming increasingly important factors to consider in the steel production process. In steel production, iron-containing raw materials need to be processed by a sintering system before entering the blast furnace for smelting. That is, various powdered iron-containing raw materials are mixed with appropriate amounts of fuel (coal powder, coke powder) and flux, and an appropriate amount of fresh water is added. After mixing and pelletizing, they are placed on a sintering trolley for roasting, causing a series of physicochemical changes to form easily smelted sinter. This process is called sintering.

[0036] In sintering production, the dust-laden flue gas from the main flue must undergo purification processes such as dust removal, desulfurization, and denitrification before being discharged. The mainstream method for dust removal in sintering flue gas is the use of an electrostatic precipitator (ESP) at the machine head to treat the dust in the flue gas. The amount of dust collected by the ESP accounts for approximately 2% to 4% of the sinter production. A company with an annual steel production of 10 million tons requires approximately 16 million tons of sinter, generating about 500,000 tons of dust annually. A schematic diagram of an existing large-scale sintering machine's ESP is shown below. Figure 2 As shown.

[0037] like Figure 2 As shown, the electric fields of the electrostatic precipitator at the sintering machine head are arranged in series. After the dust-laden flue gas is treated by each electric field, it enters the next process after meeting the entry standard. The dust collected by each electric field enters the ash storage bin of each electric field. The ash unloading system of each electric field's ash storage bin operates according to the set program / ash unloading sequence cycle. The dust collected by all electric fields is collected into the dust buffer bin by the dust conveying system. The dust collected in the dust buffer bin will be disposed of by the subsequent dust disposal process.

[0038] It is important to note that many ore raw materials contain high levels of alkali metal elements such as K and Na. The compounds formed by these alkali metal elements have low boiling points and can directly volatilize into the flue gas during high-temperature sintering, or be reduced by coke to the corresponding elemental metal gases, escaping and condensing in the electrostatic precipitator system. These gases then combine with Cl elements present in the raw materials and are subsequently captured and collected in the dust collector ash. The dust collector ash mainly contains various elements such as TFe, K, and Na (K and Na exist in the form of KCl and NaCl). It should be noted that existing sintering dust collector ash disposal methods generally involve:

[0039] (1) Stockpiling (transportation is considered solid waste). The problem with stockpiling is that it requires a lot of storage space, and as production continues, the accumulated dust will accumulate more and more, eventually forcing a solution to be found. Currently, all steel companies have a large amount of dust from the electrostatic precipitator stockpiled for disposal.

[0040] (2) It is directly used as a sintering raw material and re-enters the sintering batching process to participate in the sintering process again. Fe element in dust is required for the sintering process, but the re-entry of alkali metals such as K and Na into the sintering process is detrimental to subsequent sintering production and the quality of sintered ore. In addition, it will form a closed-loop dust cycle, leading to an increase in the ineffective load of the sintering system.

[0041] (3) After removing K and Na elements from the dust collector ash, it is then used in the sintering process. The dust collector ash from which K and Na elements have been removed can be used as raw material in the sintering production process without adversely affecting the sintering production. Currently, the commonly used K and Na removal process is water washing and desalination. A typical water washing and desalination process flow chart is shown below. Figure 4 As shown:

[0042] like Figure 4 As shown, sintering dust from the dust collector buffer silo and fresh production water are mixed in a slurry tank to form a slurry. The slurry undergoes solid-liquid separation in a solid-liquid separation unit. KCl and NaCl dissolve in the clear liquid and are carried away by the clear liquid to the subsequent evaporation, crystallization, and salt separation process. The filter cake enters a secondary fresh water washing process or is sent to sintering. Because the dust collector ash has a high K and Na content, multi-stage fresh water washing is required. Figure 4 (A single-stage water washing desalination system) to meet the requirements for removing K and Na elements;

[0043] like Figure 4 As shown, the primary clear liquid is sent to the evaporation, crystallization and salt separation process. The KCl and NaCl separated in the evaporation, crystallization and salt separation process can be sold as commodities. Therefore, the high content of KCl and NaCl in the filter cake is also a waste of raw materials.

[0044] It is worth noting that, as shown in Table 1 below, Table 1 is a table of the composition (mass fraction) of the dust collected by the electrostatic precipitator in each electric field of the sintering machine head of Ansteel.

[0045] Table 1. Composition of dust from the electrostatic precipitator at the sintering machine head of Ansteel (mass fraction)

[0046] Table 1Composition of electric dust in Ansteel sintering head%

[0047]

[0048] Table 1 lists the composition (mass fraction) of the dust from the electrostatic precipitators in each field of the sintering machine heads of the No. 2 and No. 3 sintering machines at Ansteel. This technical solution focuses on four components: TFe, FeO, NaCl, and KCl (highlighted by rectangular boxes in Table 1). TFe represents total iron, which is the sum of iron elements in all iron-containing components of the ore (here referring to the blast furnace head dust). It is calculated from all iron elements in metallic iron (Fe), magnetite (Fe3O4), iron oxide (Fe2O3), and ferrous oxide (FeO) in the ore. FeO is listed separately because its content is an important indicator for blast furnace production, thus it is listed separately to assess ore quality. The iron elements in the FeO column are already included in the TFe column.

[0049] As can be seen from the rectangular boxes in Table 1, the composition of the dust from the electrostatic precipitators at the sintering machine heads varies due to differences in the raw material composition of each sintering machine. However, a common characteristic is that the Fe content (TFe+FeO) is high and the alkali metal salt (NaCl+KCl) content is low in the first electric field; the Fe content (TFe+FeO) gradually decreases in subsequent electric fields, while the alkali metal salt (NaCl+KCl) content gradually increases; the composition of the dust varies considerably between the electric fields. This table is representative, and the composition distribution of the dust from the electrostatic precipitators at the sintering machine heads of steel enterprises is similar to that of Ansteel.

[0050] It should be noted that the single-field dust removal efficiency of an electrostatic precipitator is ~80%. Considering the influence of the airflow moving backward from the first field and carrying away some of the falling dust, the dust removed by the first field accounts for about 60% of the total dust removed, and the dust removed by the second field accounts for about 60% of the remaining 40%, or 24%, and so on for the other fields.

[0051] like Figure 3The electrostatic precipitator shown is a four-field type sintering electrostatic precipitator. The typical ash unloading logic of each field's ash storage bin is as follows: Figure 3 As shown, specifically, the electrostatic precipitator at the dust collector head continuously discharges ash periodically during operation. T1 in the diagram represents one standard ash discharge cycle, and subsequent ash discharges can be considered as repetitions of multiple similar standard ash discharge cycles. Figure 3 As shown, the T1 ash unloading cycle can be divided into 5 segments, namely:

[0052] TT0: The ash accumulation section of each electric field ash storage bin of the dust collector head. The ash unloading equipment of each dust removal electric field in the TT0 section is not working. The ash storage bins of each dust removal electric field store the electrostatic precipitator ash collected to form a ash storage bin material seal.

[0053] TT1: Ash discharge section of the first electric field. At this time, the ash storage bin of the first electric field is close to or reaches the high material level. The ash discharge equipment of the first electric field is working and the first electric field discharges ash. The duration of the ash discharge is TT1. The start time of the ash discharge is t1. When the ash storage bin of the first electric field is close to or reaches the low material level, the ash discharge of the first electric field ends. The end time of the ash discharge is t2.

[0054] TT2: Ash discharge section of the second electric field. At this time, the ash storage bin of the second electric field is close to or reaches the high material level. The ash discharge equipment of the second electric field is working and the second electric field discharges ash. The duration of ash discharge is TT2. The start time of ash discharge is t2. When the ash storage bin of the second electric field is close to or reaches the low material level, the ash discharge of the second electric field ends. The end time of ash discharge is t3.

[0055] TT3: Ash discharge section of the third electric field. At this time, the ash storage bin of the third electric field is close to or reaches the high material level. The ash discharge equipment of the third electric field works and the third electric field discharges ash. The duration of ash discharge is TT3. The start time of ash discharge is t3. When the ash storage bin of the third electric field is close to or reaches the low material level, the ash discharge of the second electric field ends. The end time of ash discharge is t4.

[0056] TT4: Ash discharge section of the fourth electric field. At this time, the ash storage bin of the fourth electric field is close to or reaches the high material level. The ash discharge equipment of the fourth electric field works and the fourth electric field discharges ash. The duration of ash discharge is TT4. The start time of ash discharge is t4. When the ash storage bin of the fourth electric field is close to or reaches the low material level, the ash discharge of the fourth electric field ends. The end time of ash discharge is t5.

[0057] T2 is the second ash unloading cycle, and the dust collector at the head of the machine repeats the above cycles for ash unloading.

[0058] like Figure 2 and Figure 3As shown, in actual production, each dust removal electric field has the same ash unloading capacity. The dust removal ash conveying system is configured with conveying capacity according to the ash unloading amount of a single dust removal electric field. That is, the dust removal ash conveying system usually only allows one dust removal electric field to unload ash, and does not allow two dust removal electric fields to unload ash at the same time.

[0059] Those skilled in the field should understand that Figure 2 The dust in the dust removal buffer bin is the dust removal ash. Figure 4 The raw materials for the water washing and desalination process shown. If based on... Figure 3 The existing electrostatic precipitator ash removal method shown will cause the dust collected in the dust removal ash buffer bin to be discharged according to the following conditions: Figure 1 The distribution pattern shown indicates that the dust collected from the first electric field ash storage bin of the electrostatic precipitator at the head of the machine (roughly from high to low material level) is received first, followed by the dust collected from the second electric field ash storage bin of the same head, and so on. This is based on a typical 360m... 2 Calculated using a sintering machine, one 360m 2 The sintering machine produces 10,000 tons of sintered ore daily. The dust removal ash is calculated at 3%, which is 300 tons. The ash removal cycle of the electrostatic precipitator at the machine head is 8 hours, so the ash removal volume in one ash removal cycle is 100 tons. If the normal ash storage capacity of the dust removal ash silo is 100 tons, then in the ash storage silo, there are ~60 tons of first-field dust removal ash in the continuous space of the dust removal ash storage silo, and ~24 tons of second-field dust removal ash immediately following it. The remaining electric field ash is stored in the dust removal ash storage silo in the same way.

[0060] As shown in Table 1, the composition of dust collected by the electrostatic precipitator varies significantly across different electric fields. If we consider... Figure 3 The existing electrostatic precipitator dust removal method shown will lead to the entry of dust into the machine head. Figure 4 The raw material composition of the water washing desalination method shown fluctuates greatly. Figure 4 Taking the water washing and desalination process shown as an example, as described above, the 360m... 2 Within 8 hours, the sintering machine head dust will first receive ~60t of dust from the first electric field dust collector, then ~24t of dust from the second electric field dust collector, and so on. However, due to the influence of many interfering factors during the production process, the water washing and desalination process makes it difficult to determine the composition of the subsequent raw materials.

[0061] Because the dust collected in the first electric field has high TFe and FeO content and low NaCl and KCl content, while the TFe and FeO content decreases sequentially and the NaCl and KCl content increases sequentially in subsequent electric fields, the large fluctuations and uncertainties in the raw material composition will obviously lead to large fluctuations in the filter cake yield, TFe and FeO content in the filter cake, and KCl and NaCl content in the clarified liquid of the water washing desalination method. Ultimately, this will lead to instability in the water washing desalination process. This is also the main factor causing large production fluctuations, frequent equipment failures, high production costs, and production interruptions in the existing single-stage water washing desalination process for sintering machine head electrostatic precipitator dust.

[0062] Please refer to Figures 1 to 4 The present invention provides a method for controlling the filter cake quality of a single-stage water washing desalination system, comprising the following steps:

[0063] S1, when the single-stage water washing desalination system is in a stable working state, the alkali metal salt concentration of the clear liquid produced by the solid-liquid separation device and the moisture content of the filter cake are obtained; wherein, the single-stage water washing desalination system includes a slurry tank and a solid-liquid separation device, the slurry tank receives fresh water and dust and produces a mixed slurry, and the solid-liquid separation device is used to receive the slurry and produce clear liquid and filter cake;

[0064] S2, determine the alkali metal salt content of the filter cake based on the alkali metal salt concentration of the clarified liquid and the moisture content of the filter cake, and determine whether the alkali metal salt content of the filter cake is less than the alkali metal salt control content;

[0065] S3, when the alkali metal salt content of the filter cake is less than the alkali metal salt control content, it is determined that the alkali metal in the filter cake will not be enriched in the sintering raw materials, and the filter cake is sent to the sintering batching process to participate in sintering.

[0066] Specifically, the core objective of this application is to control the alkali metal content of the filter cake, ensuring that the filter cake, when used as a sintering raw material, does not lead to alkali metal enrichment during subsequent sintering. This is achieved by obtaining the alkali metal salt concentration in the clarified liquid produced by the solid-liquid separation unit and the moisture content of the filter cake during stable (continuous production) operation of the single-stage water washing and desalination system. The alkali metal salt content in the filter cake is then determined based on these concentrations. This step is crucial for evaluating filter cake quality, as it directly affects the filter cake's performance in subsequent sintering processes. If the alkali metal content is higher than the alkali metal content, the filter cake will not be properly sintered. If the alkali metal salt content is controlled, the alkali metal content in the filter cake will be enriched in the raw materials. Since Fe element in the dust is required for the sintering process, the re-entry of alkali metals such as K and Na into the sintering process is detrimental to subsequent sintering production and the quality of sintered ore. In addition, it will form a closed-loop dust cycle, leading to an increase in the ineffective load of the sintering system. If the content is lower than the alkali metal salt control content, the alkali metal content in the filter cake will not be enriched in the raw materials. The filter cake can be used as a raw material for sintering production and will not have an adverse impact on sintering production, thus improving resource utilization.

[0067] In a preferred embodiment, step S2, determining the alkali metal salt content of the filter cake based on the alkali metal salt concentration of the clarified liquid and the moisture content of the filter cake, specifically includes the following steps: using the formula... Determine the alkali metal salt content of the filter cake; wherein, ND B1 The content of alkali metal salts in filter cake B1 is expressed in %, CM. B1 The amount of filter cake produced by the solid-liquid separation device, in kg, HS B1 ND represents the moisture content of filter cake B1, in % .G1 The concentration of the alkali metal salt in the supernatant G1 is expressed as %.

[0068] Specifically, this embodiment also provides a detailed derivation process for the formula, as follows:

[0069] Table 2: Ingredients for Sintering

[0070]

[0071] As shown in Table 2, the steel company determines the sintering batching ratio for the next production cycle based on raw material inventory and production demand. The steel company can plan different ratios based on raw material inventory and production demand. The alkali metal (K, Na) content varies in each raw material component, and the alkali metal (K, Na) content in each raw material component is known (it can be obtained through existing mature technologies, which will not be elaborated here). The alkali metal (K, Na) content of different ratios can be calculated based on the batching table. For example, the alkali metal content calculated for ratio 1 is J1, and the alkali metal content calculated for ratio 2 is J2.

[0072] As shown in Table 1, KCl is the main alkali metal salt in dust collector ash, with NaCl accounting for 5.6% and KCl accounting for 94.4%. In sintering raw materials, alkali metals exist in various forms, forming alkali metal salts (NaCl, KCl) during sintering. The alkali metal salt content in dust collector ash can be converted into alkali metal content using Formula 1:

[0073]

[0074] Where: k1 is the alkali metal content, in %; k2 is the alkali metal salt content, in %; 19 is the periodic number of element K; 17 is the periodic number of element Cl.

[0075] Because the alkali metal salts in dust are mainly KCl, NaCl accounts for 5.6% of the alkali metal salts, and KCl accounts for 94.4% of the alkali metal salts, considering the allowable deviation in engineering, and to simplify the calculation, the influence of NaCl is not considered in Formula 1 of the preferred embodiment.

[0076] If a certain sintering process is carried out using ratio 1, the alkali metal content in the sintering raw material can be J1. Under the production conditions of ratio 1, if the alkali metal content of the filter cake of the electrostatic precipitator after water washing reaches the requirements of formula 2, then the alkali metal will not be enriched in the raw material. That is, the water washing and desalination process meets the requirements for removing alkali metal.

[0077] ND B1 ×0.53×H≤J1; Formula 2

[0078]

[0079] Therefore, a control standard for alkali metal salts in filter cake B1 of the water washing and desalination process can be set:

[0080]

[0081] Wherein: ND B1 , where is the alkali metal salt content in the filter cake, in %; H is a correction factor considering engineering errors such as measurement, which can be taken as 1.0 to 1.5; J1 is the alkali metal content of sintering ratio 1, in %; k2 is the control standard for alkali metal salt content in the filter cake, in %;

[0082] As shown in Formula 3, if the alkali metal salt content in the filter cake meets the requirements of Formula 3, it means that after the filter cake re-enters the sintering batch, the alkali metal content in the filter cake is less than or equal to the alkali metal content in the sintering batch. That is, the filter cake entering the sintering process will not lead to the enrichment of alkali metals.

[0083] like Figure 4 In the water washing and desalination process shown, the slurry is separated into a clear liquid and a filter cake after passing through a solid-liquid separation device. The filter cake is not absolutely water-free; the actual filter cake moisture content achievable by the solid-liquid separation device is between 20% and 30%. The current filter cake moisture content can be obtained based on the operating conditions of the solid-liquid separation device (e.g., centrifuge speed, residence time, filter press pressure, etc.) and production experience. Under stable production conditions, the filter cake moisture content can be considered a constant. The water in the filter cake comes from the slurry, which is actually an alkali metal solution. Part of it flows through the clear liquid channel, and the remainder flows with the filter cake. The alkali metal salts in the filter cake are brought in by the alkali metal solution flowing with the filter cake. Based on the above, the alkali metal salt content in the filter cake can be calculated as shown in Formula 3b:

[0084]

[0085] Wherein: ND B1 The content of alkali metal salts in filter cake B1, in %; CM B1 The amount of filter cake produced by the solid-liquid separation device, in kg; HS B1 Water content in filter cake B1, in %; ND G1 The concentration of alkali metal salts in the supernatant G1 is expressed as a percentage (%).

[0086] Clearly, setting the control objective of the electrostatic precipitator ash washing and desalination process at the sintering plant head as maximizing the concentration of alkali metal salts in the clarified liquid while meeting the alkali metal content requirements of the filter cake is reasonable. Combining formulas 3a and 3b, it can be seen that controlling the alkali metal salt content of the filter cake to the upper limit required by formula 3 is an optimized control strategy that meets the requirements of sintering production, reduces energy consumption in subsequent evaporation, crystallization, and salt separation processes, and saves water.

[0087] In a preferred embodiment, obtaining the alkali metal salt concentration of the clarified liquid produced by the solid-liquid separation device in step S1 specifically includes the following steps: using the formula The concentration of alkali metal salts ND in the clarified liquid produced by the solid-liquid separation device was calculated. G1 Among them, LL B The dust collection flow rate added to the slurry tank during stable operation is measured in kg / s and is considered a constant under stable operating conditions. ND B The alkali metal salt content in dust B, expressed as a percentage, can be obtained through pre-detection online using an instrument. A The water flow rate added to the slurry tank under stable operating conditions is expressed in kg / s; it is considered a constant under stable operating conditions, HS. B The water content in dust B, expressed as a percentage, can be obtained through online instrument detection.

[0088] This embodiment uses theoretical calculations to obtain the alkali metal salt concentration of the clarified solution, without the need for actual experimental equipment and consumables such as concentration meters, test tubes, and reagents. Therefore, it can save experimental costs and resources. Theoretical calculations can accurately calculate the concentration of the solution. Based on the calculated alkali metal salt concentration of the clarified solution, the concentration status of the clarified solution can be quickly obtained to rapidly assess the production status.

[0089] It is understood that in other embodiments, the concentration of alkali metal salts in the supernatant can also be detected by instruments, such as a concentration meter, and the concentration of alkali metal salts in the supernatant can also be obtained.

[0090] As a preferred embodiment, when the alkali metal salt content of the filter cake is greater than or equal to the controlled alkali metal salt content, formula ND is used. GK2 =k2 / HS B1 Determine the concentration of the clarified liquid (ND) that meets the alkali metal control requirements for the filter cake. GK2 The unit is %, and k2 is the control standard for alkali metal salt content in filter cake, in %;

[0091] Using formula Determine the water supply by adding water valve AF1; where LL AK2 For continuous production in the slurry tank, add water valve AF1 to control the flow rate, in units of kg / s;

[0092] Adjust the control flow of the water valve AF1 to LL. AK2 .

[0093] Specifically, when the alkali metal salt content of the filter cake is greater than or equal to the controlled alkali metal salt content, directly feeding the filter cake as a sintering raw material to the sintering batching process will lead to alkali metal enrichment. To solve this problem, this embodiment adjusts the flow rate by adjusting the control flow rate of the water addition valve AF1 in the slurry tank, as shown by formula ND. B1 =HS B1 ×ND G1 According to formula 3b, adjusting the concentration of the clear liquid (ND) G1 The concentration of alkali metals in the filter cake can be adjusted. The flow rate of the water addition valve AF1, obtained by the flow rate adjustment formula provided in this application, can be controlled so that the filter cake, as a sintering raw material, can be sent to the sintering batching process to participate in sintering without causing alkali metal enrichment. Furthermore, it can quickly guide the flow rate control of the water addition valve AF1, achieving accurate and rapid adjustment.

[0094] As a preferred embodiment, the filter cake alkali metal salt content control standard k2 is obtained through the following steps: obtaining the sintering raw material batching ratio for a future production cycle, and determining the alkali metal content J corresponding to the sintering raw material batching ratio (in %); using the formula... Determine the control standard k2 for the alkali metal salt content of the filter cake; where H is a correction coefficient considering engineering errors.

[0095] As a preferred example, the moisture content of the filter cake is between 20% and 30%. Under stable production conditions, the moisture content of the filter cake can be considered constant.

[0096] As a preferred example, the correction factor H is set between 1.0 and 1.5.

[0097] This invention also provides a single-stage water washing and desalination system, including a slurry tank and a solid-liquid separation device. The slurry tank includes a slurry tank body, a water inlet assembly for receiving external fresh water, an ash inlet assembly for receiving dust, and a slurry outlet assembly. The water inlet assembly is equipped with a first water inlet valve, and the slurry outlet assembly is equipped with a slurry outlet valve. Water enters the slurry tank body through the water inlet assembly, and dust enters the slurry tank body through the ash inlet assembly. The water and dust mix in the slurry tank body to form a slurry. The solid-liquid separation device is used to receive the slurry from the slurry outlet assembly and produce a clear liquid and a filter cake.

[0098] Specifically, the structural form of the system in this application can be as follows: Figure 4The single-stage water washing desalination system shown receives fresh water supplied from the outside through the water inlet assembly and dust collection ash through the ash inlet assembly. Inside the slurry tank, the fresh water and dust collection ash mix to form a slurry. During this process, the water dissolves the salts in the dust collection ash. The mixed slurry is discharged through the slurry outlet assembly and then enters a solid-liquid separation device, such as a plate and frame filter press. The single-stage water washing desalination system provided in this application effectively dissolves the salts in the dust collection ash through water washing and discharges them with the clarified liquid, achieving efficient desalination of the dust collection ash and providing possibilities for subsequent resource utilization or safe disposal. This system has a simple structure, is easy to operate, and is readily automated, reducing labor costs and operational complexity.

[0099] Furthermore, a control system can be added to achieve automated control. The water inlet component and the ash inlet component are both connected to the control system. The control system includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the filter cake quality control method of the single-stage water washing desalination system described above.

[0100] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A method for controlling the quality of filter cake in a single-stage water washing desalination system, characterized in that, Including the following steps: S1, when the single-stage water washing desalination system is in a stable working state, the alkali metal salt concentration of the clear liquid produced by the solid-liquid separation device and the moisture content of the filter cake are obtained; wherein, the single-stage water washing desalination system includes a slurry tank and a solid-liquid separation device, the slurry tank receives fresh water and dust and produces a mixed slurry, and the solid-liquid separation device is used to receive the slurry and produce clear liquid and filter cake; S2, determine the alkali metal salt content of the filter cake based on the alkali metal salt concentration of the clarified liquid and the moisture content of the filter cake, and determine whether the alkali metal salt content of the filter cake is less than the alkali metal salt control content; S3, when the alkali metal salt content of the filter cake is less than the alkali metal salt control content, it is determined that the alkali metal in the filter cake will not be enriched in the sintering raw materials, and the filter cake is sent to the sintering batching process to participate in sintering.

2. The filter cake quality control method of the single-stage water washing desalination system according to claim 1, characterized in that, Step S2, determining the alkali metal salt content of the filter cake based on the alkali metal salt concentration of the clarified liquid and the moisture content of the filter cake, specifically includes the following steps: using the formula... Determine the alkali metal salt content of the filter cake; wherein, The alkali metal salt content of filter cake B1 is expressed as a percentage. The amount of filter cake produced by the solid-liquid separation device, in kg. The moisture content of filter cake B1 is expressed as a percentage. The concentration of the alkali metal salt in the supernatant G1 is expressed in units.

3. The filter cake quality control method of the single-stage water washing desalination system according to claim 2, characterized in that, The step S1 of obtaining the alkali metal salt concentration of the clarified liquid produced by the solid-liquid separation device specifically includes the following steps: using the formula The concentration of alkali metal salts in the clarified liquid produced by the solid-liquid separation device was calculated. ;in, To ensure stable operation, the slurry tank needs to be filled with dust collector ash at a rate of kg / s. The content of alkali metal salts in dust B is expressed as a percentage. The water flow rate added to the slurry tank to ensure stable operation is expressed in kg / s. The water content in dust B is expressed in units of %.

4. The filter cake quality control method of the single-stage water washing desalination system according to claim 3, characterized in that, When the alkali metal salt content of the filter cake is greater than or equal to the controlled alkali metal salt content. Using formula ND GK2 =k2 / HS B1 Determine the concentration of the clarified liquid (ND) that meets the alkali metal control requirements for the filter cake. GK2 ,unit%, The standard for controlling the alkali metal salt content in filter cake is expressed in % (%). Using formula Determine to add water valve AF1 to adjust the water flow; among which, For continuous production in the slurry tank, add water valve AF1 to control the flow rate, in units of kg / s; Adjust the control flow of the water valve AF1 to [the appropriate level]. .

5. The filter cake quality control method of the single-stage water washing desalination system according to claim 4, characterized in that, Filter cake alkali metal salt content control standard Specifically, it is obtained through the following steps: Obtain the sintering raw material batching ratio for the next production cycle and determine the corresponding alkali metal content. ,unit%; Using formula Determine the control standard for alkali metal salt content in filter cake ;in, Correction factors to account for engineering errors.

6. The method for controlling the filter cake quality of a single-stage water washing desalination system according to claim 1, characterized in that, The moisture content of the filter cake is between 20% and 30%.

7. The method for controlling the filter cake quality of a single-stage water washing desalination system according to claim 5, characterized in that, Correction coefficient Set between 1.0 and 1.

5.

8. A single-stage water washing desalination system, used to perform the filter cake quality control method of the single-stage water washing desalination system as described in any one of claims 1-7, characterized in that, The system includes a slurry tank and a solid-liquid separation device. The slurry tank comprises a slurry tank body, a water inlet assembly for receiving external fresh water, an ash inlet assembly for receiving dust collector ash, and a slurry outlet assembly. The water inlet assembly is equipped with a first water inlet valve, and the slurry outlet assembly is equipped with a slurry outlet valve. Water enters the slurry tank body through the water inlet assembly, and dust collector ash enters the slurry tank body through the ash inlet assembly. The water and dust collector ash mix in the slurry tank body to form a slurry. The solid-liquid separation device is used to receive the slurry from the slurry outlet assembly and produce a clear liquid and a filter cake.

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