Method for recovering and treating dedusting ash of sintering machine head

Abstract

The invention discloses a sintering machine head fly ash recovery treatment method, which comprises a washing reaction process and an evaporative crystallization process, the washing reaction process adopts first-stage washing, the evaporative crystallization process adopts two-effect evaporation, and the washing reaction process comprises the following steps: S1, preparing fly ash and water into slurry according to a certain ratio, storing the slurry in a slurry tank, and sampling the slurry; s2, measuring the solid-to-liquid ratio according to the raw ash components of the sintering machine head fly ash, pumping the slurry into a diaphragm filter press for filtering after the requirements are met, returning a filter cake to the sintering ingredient, and enabling the filtrate to enter a filtrate tank; according to the method, the sintering machine head dedusting ash is subjected to washing desalination to reduce hardness and remove insoluble impurities, and generated high-salt ash washing water is subjected to double-effect evaporative crystallization and centrifugal separation to realize crystallization and separation of a potassium chloride product. The iron element in the fly ash is recycled, the requirement that solid waste does not leave a factory in the iron and steel industry is met, generated potassium chloride is sold as a product, and the method has important significance on high-quality development of enterprises.

Description

Technical Field

[0001] The invention relates to the field of comprehensive utilization of industrial waste and building materials, and in particular to a method for recycling dust from a sintering machine head. Background Art

[0002] The annual production of sintering machine head ash in the Taigang plant is about 14,000 tons, which contains high content of useful elements such as iron, potassium and sodium. If it is not treated as a resource, it will not only waste valuable resources, but also cause these components to accumulate in the system, thus affecting the use of equipment.

[0003] The solubility of potassium chloride solution increases with increasing temperature. When the temperature increases from 20°C to 100°C, the solubility increases from 34 to 56.7. The solubility gradient is large. By using reverse cooling, the potassium chloride in the potassium chloride solution can easily be supersaturated and precipitated, thereby extracting the potassium chloride in the solution.

[0004] The existing water washing process mostly adopts two-stage or even three-stage water washing, which has a long process flow, three-effect evaporation and crystallization, large equipment investment, and many process control points. Therefore, we propose a method for recycling and treating dust from sintering machine heads. Summary of the invention

[0005] The purpose of the present invention is to provide a method for recycling dust from a sintering machine head to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above purpose, a method for recycling dust from a sintering machine head includes a water washing reaction process and an evaporation crystallization process. The water washing reaction process adopts a primary water washing process, and the water washing reaction process includes the following steps:

[0007] S1. Mix dust removal ash and water in a certain ratio to make slurry, store it in a slurry tank, and sample the slurry;

[0008] S2. Measure the solid-liquid ratio according to the raw ash composition of the sintering machine head dust removal ash. If it meets the requirements, the slurry is pumped into the diaphragm filter press for filtration, the filter cake is returned to the sintering ingredients, and the filtrate enters the filtrate tank;

[0009] S3, sampling the filtrate tank, measuring the salt concentration, and pumping the filtrate into the reaction tank after meeting the requirements;

[0010] S4, adding a softener to the reaction tank to reduce the hardness of the filtrate and remove Ca impurities, then adding liquid alkali to adjust the pH of the filtrate, then adding a heavy supplement to remove Cu, Pb, and Zn impurities, and then adding a flocculant to remove organic matter and suspended impurities and accelerate the precipitation rate;

[0011] S5. Test the solution after the reaction. When the pH, color and transparency meet the requirements, the solution is pumped back to the filter press, the filter cake is returned to the sintering ingredients, and the filtrate enters the regulating tank;

[0012] S6. Test the solution in the adjustment tank and let it enter the buffer tank if it meets the requirements.

[0013] Preferably, the evaporation and crystallization process adopts two-effect evaporation, and the evaporation and crystallization process comprises the following steps:

[0014] Step 1: The solution in the buffer tank enters the first-effect heater through the preheater, circulates in the first-effect heater and the separator to a certain concentration and enters the second-effect heater;

[0015] Step 2: Circulate in the second-effect heater and separator, add defoamer, and enter the thickening kettle after the salt content is qualified;

[0016] Step 3: Stirring and thickening the solution in a thickening kettle, and the thickened solution enters a centrifuge for solid-liquid separation;

[0017] Step 4: Potassium chloride salt is transported into ton bags through a screw conveyor for packaging, and the separated solution enters the mother liquid tank as a supplement for the second-effect heater.

[0018] Preferably, the K content in the sintering machine dust is 9% to 17%; and the concentration of the slurry in the slurry tank in step S1 is 20% to 35%.

[0019] Preferably, in step S2, the feed pressure of the membrane filter press is 0.6-0.8 MPa, and the filtration cycle is 1000-1500 seconds.

[0020] Preferably, the salt content in the filtrate tank in step S3 is 10% to 12%.

[0021] Preferably, the addition ratio of the reagents in the reaction tank in step S4 is 3% to 8% of softener, 1% to 3% of liquid alkali, 0.1% to 0.5% of rehydrating agent, and 0.005% to 0.008% of flocculant.

[0022] Preferably, the pH of the solution after the reaction in step S5 is 11.2, the solution in the adjustment tank is transparent, and the color of the solution in the adjustment tank is light yellow.

[0023] Preferably, in the step 2, 0.01% to 0.05% of defoaming agent is added to the second-effect heater, and the salt content in the second-effect separator is 15%.

[0024] Preferably, the frequency of the centrifuge in step three is 35-50 Hz, and the potassium chloride salt in step four has a K2O content of 55%-60% and a water content of 1%-6%.

[0025] Preferably, the filter cake in step S2 contains 1% to 5% residual K and 5% to 30% moisture.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention washes and evaporates the dust from the sintering machine head, and the produced potassium chloride is directly exported as agricultural potassium fertilizer to generate income for the enterprise; the iron-rich powder and heavy mud cake after treatment are all returned to the sintering ingredients to achieve full reuse of iron elements; the iron element in the machine head ash is recovered and the potassium element is extracted and commercialized, which meets the requirements of the steel industry to prevent solid waste from leaving the factory and reduce costs and increase efficiency.

[0028] 2. The water washing process of the present invention adopts one-stage water washing and one-stage filter pressing, which has a simple process flow and high ash washing efficiency, avoiding blockage caused by long-distance transportation of slurry. The salt concentration of the filtrate after filter pressing is low, and the filtrate can be returned for re-washing. The evaporation and crystallization process adopts double-effect evaporation to maximize the use of steam waste heat. The steam condensate is fully reused in the system, and waste water is not discharged. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0031] See also Figure 1 The present invention provides a technical solution: a method for recycling dust from a sintering machine head, comprising a water washing reaction process and an evaporation crystallization process, wherein the water washing reaction process adopts a primary water washing process, and the water washing reaction process comprises the following steps:

[0032] S1. Mix dust removal ash and water in a certain ratio to make slurry, store it in a slurry tank, and sample the slurry;

[0033] S2. Measure the solid-liquid ratio according to the raw ash composition of the sintering machine head dust removal ash. If it meets the requirements, the slurry is pumped into the diaphragm filter press for filtration, the filter cake is returned to the sintering ingredients, and the filtrate enters the filtrate tank;

[0034] S3, sampling the filtrate tank, measuring the salt concentration, and pumping the filtrate into the reaction tank after meeting the requirements;

[0035] S4, adding a softener to the reaction tank to reduce the hardness of the filtrate and remove impurities such as Ca, then adding liquid alkali to adjust the pH of the filtrate, then adding a heavy supplement to remove impurities such as Cu, Pb, Zn, and then adding a flocculant to remove impurities such as organic matter and suspended matter and accelerate the precipitation rate;

[0036] S5. Test the solution after the reaction. When the pH, color and transparency meet the requirements, the solution is pumped back to the filter press, the filter cake is returned to the sintering ingredients, and the filtrate enters the regulating tank;

[0037] S6. Test the solution in the adjustment tank and let it enter the buffer tank if it meets the requirements.

[0038] It should be noted that the sintering machine head dust removal ash adopts a primary water washing and desalination method to reduce pipeline transportation, maximize water washing efficiency, simplify process flow and process control points, and the machine head ash filter cake is returned to the sintering ingredients after water washing. The high-salt ash washing water produced enters the subsequent impurity removal and purification system, and the drug is added in the same reaction tank. The heavy metals (Cu, Pb, Zn), hardness, suspended matter, etc. in the high-salt ash washing water are synergistically removed by one-step reaction, and then the impurities in the solution are removed by filter pressing. The high-salt brine after impurity removal and purification is crystallized, separated, and dried by two-effect evaporation and centrifugation. The two-effect evaporation improves the efficiency of the use of steam heat source, and the quality of potassium chloride products meets the agricultural potash fertilizer standards.

[0039] The evaporation and crystallization process adopts two-effect evaporation, and the evaporation and crystallization process includes the following steps:

[0040] Step 1: The solution in the buffer tank enters the first-effect heater through the preheater, circulates in the first-effect heater and the separator to a certain concentration and enters the second-effect heater;

[0041] Step 2: Circulate in the second-effect heater and separator, add defoamer, and enter the thickening kettle after the salt content is qualified;

[0042] Step 3: Stirring and thickening the solution in a thickening kettle, and the thickened solution enters a centrifuge for solid-liquid separation;

[0043] Step 4: Potassium chloride salt is transported into ton bags through a screw conveyor for packaging, and the separated solution enters the mother liquid tank as a supplement for the second-effect heater.

[0044] It should be noted that if the salt content of the filtrate after water washing is insufficient, it can be returned to pulping for re-mixing. The heat source in the system is medium-pressure steam. The condensed water generated by the medium-pressure steam after heat exchange with the first-effect heater enters the steam condensate tank as circulating water replenishment for the equipment system. The steam generated by the first-effect heater enters the second-effect heater to heat the solution. The primary steam generated by the second-effect heater passes through the preheater to preliminarily heat the solution entering the first effect. After the steam is cooled, it enters the condensate storage tank for use as pulping water. The mother liquor separated from the thickening kettle enters the second-effect heater for evaporation again. The system maximizes the utilization of steam heat and achieves no wastewater discharge.

[0045] Among them, the softener is industrial sodium carbonate, the refilling agent is sodium sulfide, the flocculant is polyacrylamide, the defoaming agent is polyether modified silicon defoaming agent, and the K content in the sintering machine dust removal ash is 9% to 17%; the concentration of the slurry in the slurry tank in step S1 is 20% to 35%; the feed pressure of the diaphragm filter press in step S2 is 0.6 to 0.8 MPa, and the filter pressing cycle is 1000 to 1500 seconds; the salt content in the filtrate tank in step S3 is 10% to 12%; the addition ratio of the reagents in the reaction tank in step S4 is 3% to 8% of the softener, 1% to 3% of the liquid alkali, and 0.1% to 0.01% of the refilling agent. .5%, flocculant 0.005%~0.008%, and the concentration of liquid alkali is 40%; the pH of the solution after the reaction in step S5 is above 11, the solution in the regulating tank is transparent and the color of the solution in the regulating tank is light yellow; in step 2, 0.01%~0.05% of defoaming agent is added to the second-effect heater, and the salt content in the second-effect separator is above 12%; the frequency of the centrifuge in step 3 is 35~50HZ, the K2O content in the potassium chloride salt in step 4 is 55%~60%, and the water content is less than 6%; the residual K in the filter cake in step S2 is 1%~5%, and the water content is less than 30%.

[0046] The present invention extracts and separates potassium chloride and the like in the dust removal ash of the sintering machine head and then returns it to sintering, which can significantly increase the content of iron in the dust removal ash of the sintering machine head. The removal of alkali metals can effectively reduce the risks of corrosion of the sintering system, with significant economic benefits. At the same time, the potassium element is extracted as a resource such as a raw material for potassium fertilizer, which is in line with the national industrial development direction. In short, the resource utilization of the dust removal ash of the sintering machine head has important practical significance and actual value for the development and realization of the circular economy of the enterprise.

[0047] Example 1

[0048] A method for recycling dust from a sintering machine head includes a water washing reaction process and an evaporation crystallization process. The water washing reaction process adopts a primary water washing process. The water washing reaction process includes the following steps:

[0049] S1. The K content in the dust removal ash from the sintering machine head is 12%. The dust removal ash and water are mixed into a slurry with a concentration of 35%, and the slurry is stored in a slurry tank, and the slurry is sampled;

[0050] S2. Measure the solid-liquid ratio according to the raw ash composition of the sintering machine head dust removal ash. If it meets the requirements, pump the slurry into the membrane filter press for filtration. The feed pressure of the membrane filter press is 0.8MPa, the filtration cycle is 1400 seconds, the K residue in the filter cake is 3%, the water content is 18%, the filter cake is returned to the sintering ingredients, and the filtrate enters the filtrate tank;

[0051] S3, sampling the filtrate tank and measuring the salt concentration. When the salt content in the filtrate tank is 11%, the filtrate is pumped into the reaction tank;

[0052] S4. Add 3% of softener (industrial sodium carbonate) to the reaction tank to reduce the hardness of the filtrate and remove impurities such as Ca, then add 1% of liquid alkali to adjust the pH of the filtrate, the concentration of the liquid alkali is 40%, then add 0.1% of heavy supplement (sodium sulfide) to remove impurities such as Cu, Pb, Zn, etc., and then add 0.006% of flocculant (polyacrylamide) to remove impurities such as organic matter and suspended matter and accelerate the precipitation speed;

[0053] S5. Test the solution after the reaction. When the pH, color and transparency meet the requirements, the solution is pumped back to the filter press, the filter cake is returned to the sintering ingredients, and the filtrate enters the regulating tank;

[0054] S6. Test the solution in the adjustment tank and let it enter the buffer tank if it meets the requirements.

[0055] The evaporation and crystallization process adopts two-effect evaporation, and the evaporation and crystallization process includes the following steps:

[0056] Step 1: The solution in the buffer tank enters the first-effect heater through the preheater, circulates in the first-effect heater and the separator to a certain concentration and enters the second-effect heater;

[0057] Step 2: Circulate in the second-effect heater and separator, add 0.02% defoamer, the concentration of the defoamer is 30%, and enter the thickening kettle after the salt content is qualified;

[0058] Step 3: Stir and thicken the solution in the thickening kettle, and after thickening, the solution enters the centrifuge for solid-liquid separation, and the centrifuge frequency is 40HZ;

[0059] Step 4: Potassium chloride salt is transported to ton bags for packaging through a screw conveyor. The K2O content in the potassium salt is 55%, and the water content is 3%. The separated solution enters the mother liquid tank as a supplement for the second-effect heater.

[0060] Example 2

[0061] A method for recycling dust from a sintering machine head includes a water washing reaction process and an evaporation crystallization process. The water washing reaction process adopts a primary water washing process. The water washing reaction process includes the following steps:

[0062] S1. The K content in the dust removal ash of the sintering machine head is 15%. The dust removal ash and water are mixed into a slurry with a concentration of 30%, and the slurry is stored in a slurry tank, and the slurry is sampled;

[0063] S2. Measure the solid-liquid ratio according to the raw ash composition of the sintering machine head dust removal ash. If it meets the requirements, pump the slurry into the membrane filter press for filtration. The feed pressure of the membrane filter press is 0.7MPa, the filtration cycle is 1500 seconds, the K residue in the filter cake is 2.8%, the water content is 18%, the filter cake is returned to the sintering batching, and the filtrate enters the filtrate tank;

[0064] S3, sampling the filtrate tank and measuring the salt concentration. When the salt content in the filtrate tank is 11%, the filtrate is pumped into the reaction tank;

[0065] S4. Add 4% of softener (industrial sodium carbonate) to the reaction tank to reduce the hardness of the filtrate and remove impurities such as Ca, then add 1.5% of liquid alkali to adjust the pH of the filtrate, the concentration of the liquid alkali is 40%, then add 0.2% of heavy supplement (sodium sulfide) to remove impurities such as Cu, Pb, Zn, and then add 0.006% of flocculant (polyacrylamide) to remove impurities such as organic matter and suspended matter and accelerate the precipitation speed;

[0066] S5. Test the solution after the reaction. When the pH, color and transparency meet the requirements, the solution is pumped back to the filter press, the filter cake is returned to the sintering ingredients, and the filtrate enters the regulating tank;

[0067] S6. Test the solution in the adjustment tank and let it enter the buffer tank if it meets the requirements.

[0068] The evaporation and crystallization process adopts two-effect evaporation, and the evaporation and crystallization process includes the following steps:

[0069] Step 1: The solution in the buffer tank enters the first-effect heater through the preheater, circulates in the first-effect heater and the separator to a certain concentration and enters the second-effect heater;

[0070] Step 2: Circulate in the second-effect heater and separator, add 0.02% defoamer, the concentration of the defoamer is 30%, and enter the thickening kettle after the salt content is qualified;

[0071] Step 3: Stir and thicken the solution in the thickening kettle, and after thickening, the solution enters the centrifuge for solid-liquid separation. The centrifuge frequency is 45HZ;

[0072] Step 4: Potassium chloride salt is transported to ton bags for packaging through a screw conveyor. The K2O content in the potassium salt is 57%, and the moisture content is 2%. The separated solution enters the mother liquid tank as a supplement for the second-effect heater.

[0073] Example 3

[0074] A method for recycling dust from a sintering machine head includes a water washing reaction process and an evaporation crystallization process. The water washing reaction process adopts a primary water washing process. The water washing reaction process includes the following steps:

[0075] S1. The K content in the dust removal ash from the sintering machine head is 17%. The dust removal ash and water are mixed into a slurry with a concentration of 28%, and the slurry is stored in a slurry tank, and the slurry is sampled;

[0076] S2. Measure the solid-liquid ratio according to the raw ash composition of the sintering machine head dust removal ash. If it meets the requirements, pump the slurry into the membrane filter press for filtration. The feed pressure of the membrane filter press is 0.8MPa, the filtration cycle is 1500 seconds, the K residue in the filter cake is 2.5%, the water content is 17%, the filter cake is returned to the sintering batching, and the filtrate enters the filtrate tank;

[0077] S3, sampling the filtrate tank and measuring the salt concentration. When the salt content in the filtrate tank is 12%, the filtrate is pumped into the reaction tank;

[0078] S4. Add 5% of softener (industrial sodium carbonate) to the reaction tank to reduce the hardness of the filtrate and remove impurities such as Ca, then add 2% of liquid alkali to adjust the pH of the filtrate, the concentration of the liquid alkali is 40%, then add 0.3% of heavy supplement (sodium sulfide) to remove impurities such as Cu, Pb, Zn, and then add 0.006% of flocculant (polyacrylamide) to remove impurities such as organic matter and suspended matter and accelerate the precipitation speed;

[0079] S5. Test the solution after the reaction. When the pH, color and transparency meet the requirements, the solution is pumped back to the filter press, the filter cake is returned to the sintering ingredients, and the filtrate enters the regulating tank;

[0080] S6. Test the solution in the adjustment tank and let it enter the buffer tank if it meets the requirements.

[0081] The evaporation and crystallization process adopts two-effect evaporation, and the evaporation and crystallization process includes the following steps:

[0082] Step 1: The solution in the buffer tank enters the first-effect heater through the preheater, circulates in the first-effect heater and the separator to a certain concentration and enters the second-effect heater;

[0083] Step 2: Circulate in the second-effect heater and separator, add 0.02% defoamer, the concentration of the defoamer is 30%, and enter the thickening kettle after the salt content is qualified;

[0084] Step 3: Stir and thicken the solution in the thickening kettle, and after thickening, the solution enters the centrifuge for solid-liquid separation, and the centrifuge frequency is 50HZ;

[0085] Step 4: Potassium chloride salt is transported into ton bags for packaging through a screw conveyor. The K2O content in the potassium salt is 58%, and the moisture content is 2%. The separated solution enters the mother liquid tank as a supplement for the second-effect heater.

[0086] To sum up, the present invention uses water washing and desalination to reduce the hardness and remove insoluble impurities of the sintering machine head dust ash. The generated high-salt ash washing water is crystallized and separated by double-effect evaporation crystallization and centrifugal separation to achieve crystallization and separation of potassium chloride products, thereby recovering the iron element in the dust ash, meeting the requirements of the steel industry that no solid waste should leave the factory. The generated potassium chloride is sold as a product, which is of great significance to the high-quality development of the enterprise.

[0087] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for recycling dust from a sintering machine head, characterized in that: The method comprises a water washing reaction process and an evaporation crystallization process. The water washing reaction process adopts a primary water washing process. The water washing reaction process comprises the following steps: S1. Mix dust removal ash and water in a certain ratio to make slurry, store it in a slurry tank, and sample the slurry; S2. Measure the solid-liquid ratio according to the raw ash composition of the sintering machine head dust removal ash. If it meets the requirements, the slurry is pumped into the diaphragm filter press for filtration, the filter cake is returned to the sintering ingredients, and the filtrate enters the filtrate tank; S3, sampling the filtrate tank, measuring the salt concentration, and pumping the filtrate into the reaction tank after meeting the requirements; S4, adding a softener to the reaction tank to reduce the hardness of the filtrate and remove Ca impurities, then adding liquid alkali to adjust the pH of the filtrate, then adding a heavy supplement to remove Cu, Pb, and Zn impurities, and then adding a flocculant to remove organic matter and suspended impurities and accelerate the precipitation rate; S5. Test the solution after the reaction. When the pH, color and transparency meet the requirements, the solution is pumped back to the filter press, the filter cake is returned to the sintering ingredients, and the filtrate enters the regulating tank; S6. Test the solution in the adjustment tank and let it enter the buffer tank if it meets the requirements.

2. The method for recycling dust from a sintering machine head according to claim 1, characterized in that: The evaporation and crystallization process adopts two-effect evaporation, and the evaporation and crystallization process includes the following steps: Step 1: The solution in the buffer tank enters the first-effect heater through the preheater, circulates in the first-effect heater and the separator to a certain concentration and enters the second-effect heater; Step 2: Circulate in the second-effect heater and separator, add defoamer, and enter the thickening kettle after the salt content is qualified; Step 3: Stirring and thickening the solution in a thickening kettle, and the thickened solution enters a centrifuge for solid-liquid separation; Step 4: Potassium chloride salt is transported into ton bags through a screw conveyor for packaging, and the separated solution enters the mother liquid tank as a supplement for the second-effect heater.

3. The method for recycling dust from a sintering machine head according to claim 1, characterized in that: The K content in the sintering machine dust is 9% to 17%; the concentration of the slurry in the slurry tank in step S1 is 20% to 35%.

4. The method for recycling dust from a sintering machine head according to claim 1, characterized in that: In step S2, the feed pressure of the membrane filter press is 0.6-0.8 MPa, and the filtration cycle is 1000-1500 seconds.

5. The method for recycling sintering machine head dust according to claim 1, characterized in that: The salt content in the filtrate tank in step S3 is 10% to 12%.

6. The method for recycling dust from a sintering machine head according to claim 1, characterized in that: The added proportions of the reagents in the reaction tank in step S4 are 3% to 8% of softener, 1% to 3% of liquid alkali, 0.1% to 0.5% of refilling agent, and 0.005% to 0.008% of flocculant.

7. The method for recycling dust from a sintering machine head according to claim 1, characterized in that: The pH of the solution after the reaction in step S5 is 11.2, the solution in the adjustment tank is transparent, and the color of the solution in the adjustment tank is light yellow.

8. The method for recycling sintering machine head dust according to claim 2, characterized in that: In the step 2, 0.01% to 0.05% of defoaming agent is added to the second-effect heater, and the salt content in the second-effect separator is 15%.

9. The method for recycling sintering machine head dust according to claim 2, characterized in that: The frequency of the centrifuge in step 3 is 35-50 Hz, and the potassium chloride salt in step 4 has a K2O content of 55%-60% and a water content of 1%-6%.

10. The method for recycling dust from a sintering machine head according to claim 1, characterized in that: The filter cake in step S2 contains 1-5% K residue and 5-30% moisture.

Images