Fly ash treatment method

Abstract

The invention provides a fly ash treatment method, and belongs to the technical field of water treatment. The fly ash treatment method provided by the invention comprises the following steps: washing fly ash with water to obtain first ash and high-salinity water; the washing water is discharged water of circulating cooling water of the waste incineration power plant; the high-salinity water is purified, and purified high-salinity water and second ash residues are obtained; the purified high-salinity water is electrolyzed, and a pypocholoride solution is obtained; dehydrating the first ash and the second ash, and then mixing with cement to obtain a mixture; sequentially granulating and curing the mixture to obtain a cured product; and the solid matter enters a garbage incinerator to be incinerated, and slag is obtained. Fly ash is washed by using discharged water of circulating cooling water of the waste incineration power plant, so that the cost is reduced; a compact wrapping layer can be formed on the surface of the ash by adopting the cement, dioxin in the ash is subjected to anaerobic decomposition in the incineration process, and resource utilization can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a method for treating fly ash. Background Art

[0002] The flue gas purification system of domestic waste incineration facilities captures the bottom ash settled at the bottom of the flue and chimney, referred to as fly ash. Since fly ash contains toxic and harmful substances such as dioxins and heavy metals, it is a hazardous solid waste and needs to be stabilized and safely treated and disposed of.

[0003] At present, fly ash is mainly disposed of by external transportation and landfilling, but external transportation will result in high transportation costs, and the heavy metals in the fly ash after landfill will gradually dissolve with environmental changes, causing pollution of surrounding water and soil, leading to secondary pollution. Therefore, how to improve the fly ash treatment process to solve the secondary pollution and waste of land resources caused by fly ash landfill treatment, and reduce the cost of reagents and transportation has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0004] The purpose of the present invention is to provide a method for treating fly ash. The method provided by the present invention realizes the resource treatment of fly ash, avoids secondary pollution, and reduces costs.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: The present invention provides a method for processing fly ash, comprising the following steps: (1) washing the fly ash with water to obtain first ash residue and high brine; the water used for washing is the external drainage of circulating cooling water of the waste incineration power plant; (2) purifying the high-salt water obtained in step (1) to obtain purified high-salt water and second ash; (3) electrolyzing the purified high-salt water obtained in step (2) to obtain a hypochlorite solution; (4) dehydrating the first ash obtained in step (1) and the second ash obtained in step (2), and then mixing them with cement to obtain a mixture; (5) granulating and curing the mixture obtained in step (4) in sequence to obtain a solidified product; (6) placing the solidified material obtained in step (5) into a waste incinerator for incineration to obtain slag; There is no order of precedence for steps (3) and (4) to (6).

[0006] Preferably, in step (1), the ratio of the volume of the external drainage of the circulating cooling water of the waste incineration power plant to the mass of the fly ash is (2-8) mL: 1 g.

[0007] Preferably, the number of water washing in step (1) is 3 to 5 times.

[0008] Preferably, the water washing in step (1) is carried out under stirring conditions.

[0009] Preferably, the purification in step (2) comprises the following steps: 1) Adjusting the pH value of the high-salt water to 7.5-8.5, then mixing the high-salt water with water-soluble carbonate to carry out a precipitation reaction to obtain a high-salt water containing precipitation; 2) The high-salt water containing precipitates obtained in step 1) is mixed with a flocculant and flocculated to obtain purified high-salt water and second ash.

[0010] Preferably, the method of adjusting the pH value of the high-salt water in step 1) includes aeration with carbon dioxide or adding dilute hydrochloric acid.

[0011] Preferably, the carbon dioxide aeration rate is 0.1-1.0 L / min.

[0012] Preferably, the precipitation reaction time in step 1) is 30 to 90 minutes.

[0013] Preferably, the mass of the flocculant in step 2) is 0.001-0.005% of the mass of the high-salt water containing the precipitate.

[0014] Preferably, the electrolysis in step (3) is intermittent electrolysis.

[0015] The invention provides a method for treating fly ash, comprising the following steps: washing the fly ash with water to obtain a first ash slag and a high-salt water; the water for washing is the external drainage of circulating cooling water of a waste incineration power plant; purifying the high-salt water to obtain purified high-salt water and a second ash slag; electrolyzing the purified high-salt water to obtain a hypochlorite solution; dehydrating the first ash slag and the second ash slag, and then mixing them with cement to obtain a mixture; granulating and solidifying the mixture in sequence to obtain a solidified product; and incinerating the solidified product in a waste incinerator to obtain slag. The present invention uses the external drainage of circulating cooling water of the garbage incineration power plant to wash the fly ash, so as to realize the resource utilization of the external drainage and reduce the cost. Meanwhile, during the water washing, the soluble chloride salt in the fly ash will be gradually dissolved from the solid phase to the liquid phase aqueous solution, and then the heavy metals in the high salt water can be removed by purification. The ash slag is mixed with cement, and the slag is successively granulated and solidified before entering the garbage incinerator for incineration. The cement will form a dense coating layer on the surface of the ash slag, so that the dioxins in the ash slag are anaerobically decomposed during the incineration process, and the heavy metals are fixed in the solidified material. The slag finally obtained is a general solid waste and can be recycled. The purified high salt water is electrolyzed (the internal electricity of the garbage incineration power plant can be used) to obtain a hypochlorite solution (which can be sold as a disinfectant), so as to realize the resource treatment of the fly ash and avoid secondary pollution. Experimental results show that the fly ash washing reduction in the fly ash treatment method provided by the present invention is 35-45%. The washed fly ash is dehydrated and mixed with cement for granulation and solidification, and then the fly ash is incinerated in a waste incinerator to become slag. The waste incineration power plant no longer generates fly ash for external treatment, thereby reducing the fly ash treatment cost and realizing the in-situ resource utilization of fly ash. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a process flow chart of fly ash treatment of the present invention; Figure 2 It is a process flow chart of purification in the present invention. DETAILED DESCRIPTION

[0017] The present invention provides a method for processing fly ash, comprising the following steps: (1) washing the fly ash with water to obtain first ash residue and high brine; the water used for washing is the external drainage of circulating cooling water of the waste incineration power plant; (2) purifying the high-salt water obtained in step (1) to obtain purified high-salt water and second ash; (3) electrolyzing the purified high-salt water obtained in step (2) to obtain a hypochlorite solution; (4) dehydrating the first ash obtained in step (1) and the second ash obtained in step (2), and then mixing them with cement to obtain a mixture; (5) granulating and curing the mixture obtained in step (4) in sequence to obtain a solidified product; (6) placing the solidified material obtained in step (5) into a waste incinerator for incineration to obtain slag; There is no order of precedence for steps (3) and (4) to (6).

[0018] The present invention has no particular limitation on the sources of the raw materials, and commercially available products known to those skilled in the art may be used.

[0019] The treatment method provided by the present invention is applicable to any fly ash, preferably to fly ash generated by burning garbage, and more preferably to fly ash generated by garbage incineration power plants.

[0020] The present invention washes the fly ash with water to obtain first ash residue and high brine.

[0021] In the present invention, the fly ash preferably contains heavy metals and dioxins. The present invention has no particular limitation on the content of the heavy metals and dioxins, and any fly ash well known to those skilled in the art can be used.

[0022] In the present invention, the external drainage of the circulating cooling water of the waste incineration power plant is preferably the external drainage of the circulating cooling water of the boiler in the waste incineration power plant. The present invention does not need to transport the fly ash outward, but only needs to wash the fly ash in the waste incineration power plant. The water used for washing is the external drainage of the circulating cooling water of the waste incineration power plant, which realizes the resource utilization of the external drainage and reduces the cost. At the same time, during the water washing, the soluble chloride salt in the fly ash will gradually dissolve from the solid phase to the liquid phase aqueous solution, and the hypochlorite solution is obtained by electrolysis. The hypochlorite solution can be used as a disinfectant for sewage treatment plants.

[0023] In the present invention, the ratio of the volume of the external drainage of the circulating cooling water of the waste incineration power plant to the mass of the fly ash is preferably (2-8) mL: 1 g. As an embodiment, the ratio of the volume of the external drainage of the circulating cooling water of the waste incineration power plant to the mass of the fly ash can be (4-6) mL: 1 g. The present invention limits the ratio of the volume of the external drainage of the circulating cooling water of the waste incineration power plant to the mass of the fly ash within the above range, which can further improve the removal rate of soluble chloride salts in the fly ash.

[0024] In the present invention, the number of water washings is preferably 3 to 5 times; the water washing is preferably carried out under stirring conditions; the stirring speed is preferably 30 to 150 r / min; the time for each water washing is preferably 30 to 90 min; and the water washing method is preferably reverse water washing.

[0025] As an implementation mode, the water washing may be performed 3 to 4 times; the stirring speed may be 50 to 70 r / min; and the time of each water washing may be 60 to 80 min.

[0026] After obtaining the first ash and high-salt water, the present invention purifies the high-salt water to obtain purified high-salt water and second ash. The present invention can remove heavy metal ions and suspended matter in the high-salt water by purification.

[0027] In the present invention, the purification preferably comprises the following steps: 1) Adjusting the pH value of the high-salt water to 7.5-8.5, then mixing the high-salt water with water-soluble carbonate to carry out a precipitation reaction to obtain a high-salt water containing precipitation; 2) The high-salt water containing precipitates obtained in step 1) is mixed with a flocculant and flocculated to obtain purified high-salt water and second ash.

[0028] The present invention preferably adjusts the pH value of the high-salt water to 7.5-8.5, then mixes the high-salt water with a water-soluble carbonate, performs a precipitation reaction, and obtains the high-salt water containing a precipitate.

[0029] As an embodiment, the pH value of the high salt water may be 8.0.

[0030] In the present invention, the method of adjusting the pH value of the high salt water preferably includes a method of carbon dioxide aeration or adding dilute hydrochloric acid. In the present invention, adjusting the pH of the high salt water can create suitable reaction conditions for removing heavy metal ions. Since the pH value of the high salt water is generally 11-12.5, it is not easy for heavy metals and carbonate or hydroxide to react to form precipitation at this pH value, so the pH should be lowered, and carbon dioxide is introduced through aeration, so that a large amount of carbonate exists in the high salt water, and calcium carbonate precipitation is generated at the same time. The formation of calcium carbonate precipitation adsorbs part of the heavy metal ions into the precipitation, so the effect of introducing carbon dioxide is better.

[0031] In the present invention, the rate of carbon dioxide aeration is preferably 0.1-1.0 L / min. The present invention has no special limitation on the time of carbon dioxide aeration, as long as the pH value of the high salt water is ensured to be 7.5-8.5.

[0032] As an embodiment, the carbon dioxide aeration rate may be 0.3 L / min, 0.4 L / min, 0.5 L / min, 0.6 L / min, 0.7 L / min, 0.8 L / min or 0.9 L / min.

[0033] In the present invention, the mass concentration of the dilute hydrochloric acid is preferably 5-20%; the time for adding the dilute hydrochloric acid to react is preferably 30-120 minutes. The present invention has no particular limitation on the amount of the dilute hydrochloric acid, as long as the pH value of the high brine is 7.5-8.5.

[0034] As an implementation mode, the mass concentration of the dilute hydrochloric acid can be 10-15%; the time for adding the dilute hydrochloric acid to react can be 60-100 minutes.

[0035] In the present invention, the water-soluble carbonate is preferably sodium carbonate; the amount of the water-soluble carbonate is preferably 10-80 g / L. As an embodiment, the amount of the water-soluble carbonate can be 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, 50 g / L, 55 g / L, 60 g / L, 65 g / L, 70 g / L or 75 g / L. In the present invention, the water-soluble carbonate can react with the heavy metal ions in the high salt water to generate carbonate precipitation of heavy metals, and the heavy metals are removed, such as the precipitation of lead, and the equation is shown in Formula I: Formula I.

[0036] The present invention has no special limitation on the operation of mixing the high-salt water and the water-soluble carbonate, and the technical scheme for preparing the mixed material well known to those skilled in the art can be adopted.

[0037] In the present invention, the precipitation reaction time is preferably 30 to 90 minutes; the precipitation reaction temperature is preferably room temperature. As an embodiment, the precipitation reaction time can be 40 minutes, 50 minutes, 60 minutes, 70 minutes or 80 minutes.

[0038] After obtaining the high-salt water containing precipitates, the present invention preferably mixes the high-salt water containing precipitates with a flocculant to perform flocculation to obtain purified high-salt water and second ash.

[0039] In the present invention, the flocculant is preferably cationic polyacrylamide (PAM); the mass of the flocculant is preferably 0.001-0.005% of the mass of the high salt water containing precipitate. As an embodiment, the mass of the flocculant can be 0.002-0.004% of the mass of the high salt water containing precipitate.

[0040] The present invention has no particular limitation on the molecular weight of the cationic polyacrylamide, and any cationic polyacrylamide well known to those skilled in the art may be used.

[0041] The present invention has no special limitation on the operation of mixing the high-salt water containing precipitates with the flocculant, and the technical scheme for preparing the mixed material well known to those skilled in the art can be adopted.

[0042] In the present invention, the flocculation time is preferably 5 to 15 minutes. As an embodiment, the flocculation time can be 10 to 12 minutes.

[0043] After the flocculation is completed, the present invention preferably filters the flocculation product to obtain purified high-salt water and second ash.

[0044] In the present invention, the filtration is preferably performed using filter cloth. The present invention has no particular limitation on the filtration operation, and the operation well known to those skilled in the art can be used.

[0045] After obtaining the purified high-salt water and the second ash, the present invention electrolyzes the purified high-salt water to obtain a hypochlorite solution.

[0046] In the present invention, the electrolysis is preferably carried out in an electrolytic cell. The present invention has no particular limitation on the type of the electrolytic cell, and any equipment well known to those skilled in the art can be used.

[0047] In the present invention, the power source of the electrolysis is preferably direct current; the electrolysis is preferably intermittent electrolysis. In the present invention, since the concentration of calcium and magnesium ions in the purified high salt water is 10000-100000 mg / L, a large amount of scale will be generated during the electrolysis process, so intermittent electrolysis is selected.

[0048] In the present invention, the intermittent electrolysis method is preferably to equip twice as many electrolytic cells, half of the electrolytic cells are electrolyzed, and the other half of the electrolytic cells are cleaned, and the cycle is repeated. The present invention adopts the intermittent electrolysis method without removing calcium and magnesium ions in the high salt water, which reduces the cost of purifying the high salt water and removing calcium and magnesium ions, and also obtains a high-concentration hypochlorite solution, including sodium hypochlorite, calcium hypochlorite, etc.

[0049] In the present invention, the time of each electrolysis of the intermittent electrolysis is preferably 30 to 60 minutes. As an embodiment, the time of each electrolysis of the intermittent electrolysis can be 40 to 50 minutes.

[0050] In the present invention, it is preferred to use dilute hydrochloric acid to soak the electrolytic cell for 5 to 15 minutes for cleaning; the mass concentration of the dilute hydrochloric acid is preferably 5 to 10%.

[0051] In the present invention, the effective chlorine concentration of the hypochlorite solution is preferably 6000-10000 mg / L.

[0052] After obtaining the first ash and the second ash, the present invention dehydrates the first ash and the second ash, and then mixes them with cement to obtain a mixture. The present invention uses cement to form a dense coating layer on the surface of the ash, so that dioxins in the ash are decomposed in anoxic conditions during the incineration process.

[0053] In the present invention, the mass contents of soluble chlorine in the first ash and the second ash are independently preferably less than 1%.

[0054] In the present invention, the dehydration is preferably carried out by a plate-and-frame dehydration machine. The present invention has no special limitation on the operation of the dehydration, and conventional process equipment and conditions of those skilled in the art can be used.

[0055] In the present invention, the blending ratio of the cement is preferably 1-10%. As an embodiment, the blending ratio of the cement can be 2-8%, or 3-5%.

[0056] The present invention has no particular limitation on the specific type of cement, and commercially available products known to those skilled in the art may be used.

[0057] The present invention has no particular limitation on the operation of mixing with cement, and any mixing operation well known to those skilled in the art may be used.

[0058] After obtaining the mixture, the present invention sequentially granulates and solidifies the mixture to obtain a solidified product.

[0059] The present invention has no particular limitation on the granulation operation. The granulation operation may be performed by an operation well known to those skilled in the art to obtain a particle size of 2 to 10 mm.

[0060] In the present invention, the curing time is preferably 10 to 48 hours. As an embodiment, the curing time can be 12 to 20 hours, or 13 to 16 hours. The present invention has no particular limitation on the curing temperature, and it can be carried out at room temperature.

[0061] After obtaining the solidified material, the present invention puts the solidified material into a garbage incinerator for incineration to obtain slag. The present invention incinerates the solidified material to decompose dioxins in the fly ash without oxygen and fixes heavy metals in the solidified material. The obtained slag can be landfilled, can be made into building materials, etc., and does not belong to hazardous waste. Therefore, the fly ash is reduced and resourced in situ.

[0062] The present invention has no special limitation on the model of the waste incinerator, and any equipment well known to those skilled in the art may be used.

[0063] In the present invention, the incineration temperature is preferably 800-1000° C. As an embodiment, the incineration temperature may be 850-900° C.

[0064] The waste incineration power plant of the present invention has a fly ash output of 3-5%, a slag output of 20-30%, and after the solidified material is incinerated in the waste incinerator, the fly ash undergoes a dioxin decomposition and heavy metal solidification process, the fly ash is washed with water and reduced by 35-45%, and becomes slag after being incinerated in the waste incinerator. The waste incineration power plant no longer generates fly ash for external treatment, thereby reducing the fly ash treatment cost and realizing the in-situ resource utilization of the fly ash.

[0065] The invention utilizes the external drainage of circulating cooling water of the garbage incineration power plant to wash the fly ash, thereby saving the consumption of washing water compared with the conventional fly ash washing process, and recycling the water consumption of the garbage incineration power plant, thereby saving the water cost of the garbage incineration power plant and the treatment cost of the fly ash, and completing the in-situ resource utilization of the fly ash; the purification cost of the high salt water is low, the heavy metal removal effect is good, and the hypochlorite solution obtained by electrolysis is high in efficiency; the electrolysis adopts intermittent electrolysis, thereby saving the purification cost of the high salt water, and also can remove heavy metals, and the disinfection effect of the hypochlorite solution is also relatively ideal, thereby solving the problem that the fly ash generated by the incineration of the garbage power plant is transported out for landfill, which occupies a large area and is costly.

[0066] The process flow chart of fly ash treatment of the present invention is as follows Figure 1 As shown, the process flow chart of the purification of the present invention is as follows Figure 2 shown.

[0067] from Figure 1 It can be seen that the ash obtained by washing the fly ash and the ash obtained after purification and filtration are first dehydrated, then mixed with cement, and then granulated and solidified in sequence, and then returned to the incineration system for incineration; the purified high-salt water obtained by filtration is electrolyzed to obtain a hypochlorite solution.

[0068] from Figure 2 It can be seen that the pH value of the high-salt water is first adjusted with carbon dioxide or dilute hydrochloric acid, then sodium carbonate is added for precipitation reaction, and finally PAM is added for flocculation to obtain purified high-salt water.

[0069] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0070] Example 1 The treatment method of fly ash is as follows: (1) The fly ash generated by the waste incineration power plant is subjected to four-stage reverse water washing at 50 r / min stirring conditions using the external drainage of the circulating cooling water of the waste incineration power plant to obtain the first ash slag and high brine with a pH value of 12.1; wherein, the waste incineration power plant processes 1,000 tons of waste per day, the amount of fly ash generated is 30 tons / day, the external drainage of the circulating cooling water of the waste incineration power plant is 120 tons / day, and the amount of slag is 200 tons / day; the ratio of the volume of the external drainage of the circulating cooling water of the waste incineration power plant to the mass of the fly ash is 2 mL: 1 g; the time for each water washing is 90 min; (2) adjusting the pH value of the high-salt water obtained in step (1) to 8.0 by carbon dioxide aeration, then adding 20 g / L sodium carbonate, and carrying out precipitation reaction at room temperature for 30 minutes to obtain high-salt water containing precipitate; wherein the carbon dioxide aeration rate is 0.3 L / min; (3) PAM with a molecular weight of 8 million is added to the high-salt water containing precipitates obtained in step (2) for flocculation for 10 minutes, and then filtered using filter cloth to obtain 45 tons of purified high-salt water and second ash; wherein the amount of PAM used is 0.005% of the mass of the high-salt water containing precipitates; (4) The purified high-salt water obtained in step (3) is placed in an electrolytic cell for electrolysis to obtain a sodium hypochlorite solution; wherein the electrolytic cell is equipped with 8 sets of electrolytic cells of the same scale, 4 sets in a group, and when one set is cleaned, the other set continues to work; the working cycle of the electrolytic cell is: one set of electrolytic cells works for 30 minutes, and then 3 wt% dilute hydrochloric acid is introduced to soak for 15 minutes, and the time for pumping in + soaking + pumping out the dilute hydrochloric acid is 30 minutes in total; the other set of electrolytic cells continues to electrolyze while the first set is cleaned, and this process is repeated; (5) The first ash obtained in step (1) and the second ash obtained in step (3) are dehydrated by a plate-frame dehydrator and then placed in a blending bin, where cement is added and blended to obtain a mixture; wherein the blending ratio of cement is 5wt%; (6) putting the mixture obtained in step (5) into a granulator for granulation to obtain a mixture with a particle size of 5 mm, and then curing it at room temperature for 10 hours to obtain a solidified product; (7) The solidified material obtained in step (6) is placed in a waste incinerator and incinerated to obtain slag; wherein the incineration temperature is 900° C.

[0071] In the treatment method of Example 1, the fly ash loses weight by 35% and 15% after washing and incineration, respectively, and the slag output is increased to 217.475 tons / day.

[0072] Example 2 The treatment method of fly ash is as follows: (1) The fly ash generated by the waste incineration power plant is subjected to three-stage reverse water washing at 60 r / min stirring conditions using the external drainage of the circulating cooling water of the waste incineration power plant to obtain the first ash slag and high brine with a pH value of 12.5; wherein, the waste incineration power plant processes 1,500 tons of waste per day, the amount of fly ash generated is 45 tons / day, the external drainage of the circulating cooling water of the waste incineration power plant is 180 tons / day, and the amount of slag is 300 tons / day; the ratio of the volume of the external drainage of the circulating cooling water of the waste incineration power plant to the mass of the fly ash is 4 mL: 1 g; the time for each water washing is 60 min; (2) adjusting the pH value of the salt water obtained in step (1) to 7.5 with 10 wt % dilute hydrochloric acid, then adding 10 g / L sodium carbonate, and performing a precipitation reaction at room temperature for 30 min to obtain a salt water containing a precipitate; (3) PAM with a molecular weight of 6 million was added to the high brine containing precipitates obtained in step (2), and flocculated for 12 minutes, and then filtered using a filter cloth to obtain 135 tons of purified high brine and second ash; wherein the amount of PAM used was 0.003% of the mass of the high brine containing precipitates; (4) The purified high-salt water obtained in step (3) is placed in an electrolytic cell for electrolysis to obtain a sodium hypochlorite solution; wherein the electrolytic cell is equipped with 24 sets of electrolytic cells of the same scale, 4 sets in a group, and when one group is cleaned, the other group continues to work; the working cycle of the electrolytic cell is: one group of electrolytic cells works for 40 minutes, and then 3wt% dilute hydrochloric acid is introduced to soak for 10 minutes, and the dilute hydrochloric acid is pumped in + soaked + pumped out for a total of 40 minutes; the other group of electrolytic cells continues to electrolyze while the first group is cleaned, and this process is repeated; (5) The first ash obtained in step (1) and the second ash obtained in step (3) are dehydrated by a plate-frame dehydrator and then put into a blending bin, and cement is added for blending to obtain a mixture; wherein the blending ratio of cement is 8wt%; (6) putting the mixture obtained in step (5) into a granulator for granulation to obtain a mixture with a particle size of 10 mm, and then curing it at room temperature for 12 hours to obtain a cured product; (7) The solidified material obtained in step (6) is placed in a waste incinerator and incinerated to obtain slag; wherein the incineration temperature is 1000°C.

[0073] In the treatment method of Example 2, the fly ash is washed and incinerated to reduce weight by 45% and 15% respectively, and the slag output is increased to 319.98 tons / day.

[0074] Example 3 The treatment method of fly ash is as follows: (1) The fly ash generated by the waste incineration power plant is washed with three levels of reverse water using the external drainage of the circulating cooling water of the waste incineration power plant at 70 r / min stirring to obtain the first ash slag and high brine with a pH value of 12.2; wherein, a waste incineration power plant processes 1,000 tons of waste per day, the amount of fly ash generated is 35 tons / day, the external drainage of the circulating cooling water of the waste incineration power plant is 150 tons / day, and the amount of slag is 200 tons / day; the ratio of the volume of the external drainage of the circulating cooling water of the waste incineration power plant to the mass of the fly ash is 4 mL: 1 g; the time for each water washing is 60 min; (2) adjusting the pH value of the high-salt water obtained in step (1) to 8.2 by carbon dioxide aeration, then adding 25 g / L sodium carbonate, and carrying out precipitation reaction at room temperature for 30 minutes to obtain high-salt water containing precipitate; wherein the carbon dioxide aeration rate is 0.2 L / min; (3) PAM with a molecular weight of 8 million is added to the high brine containing precipitates obtained in step (2), flocculated for 12 minutes, and then filtered using filter cloth to obtain 105 tons of purified high brine and second ash; wherein the amount of PAM used is 0.004% of the mass of the high brine containing precipitates; (4) The purified high-salt water obtained in step (3) is placed in an electrolytic cell for electrolysis to obtain a sodium hypochlorite solution; wherein the electrolytic cell is equipped with 16 sets of electrolytic cells of the same scale, 4 sets in a group, and when one group is cleaned, the other group continues to work; the working cycle of the electrolytic cell is: one group of electrolytic cells works for 40 minutes, and then 3wt% dilute hydrochloric acid is introduced to soak for 10 minutes, and the dilute hydrochloric acid is pumped in + soaked + pumped out for a total of 40 minutes; the other group of electrolytic cells continues to electrolyze while the first group is cleaned, and this process is repeated; (5) The first ash obtained in step (1) and the second ash obtained in step (3) are dehydrated by a plate-frame dehydrator and then put into a blending bin, and cement is added for blending to obtain a mixture; wherein the blending ratio of cement is 10wt%; (6) putting the mixture obtained in step (5) into a granulator for granulation to obtain a mixture with a particle size of 2 mm, and then curing it at room temperature for 20 hours to obtain a solidified product; (7) The solidified material obtained in step (6) is placed in a waste incinerator and incinerated to obtain slag; wherein the incineration temperature is 900° C.

[0075] In the treatment method of Example 3, the fly ash is washed and incinerated to reduce weight by 40% and 10% respectively, and the slag output is increased to 219.6 tons / day.

[0076] It can be seen from the above embodiments that the treatment method provided by the present invention realizes the in-situ resource treatment of fly ash, the circulating cooling water of the waste incineration power plant is utilized as a resource, and the fly ash is converted into slag that does not belong to hazardous waste, thereby avoiding secondary pollution and reducing costs.

[0077] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for treating fly ash, characterized in that: The following steps are involved: (1) washing the fly ash with water to obtain first ash residue and high brine; the water used for washing is the external drainage of circulating cooling water of the waste incineration power plant; (2) purifying the high-salt water obtained in step (1) to obtain purified high-salt water and second ash; (3) electrolyzing the purified high-salt water obtained in step (2) to obtain a hypochlorite solution; (4) dehydrating the first ash obtained in step (1) and the second ash obtained in step (2), and then mixing them with cement to obtain a mixture; (5) granulating and curing the mixture obtained in step (4) in sequence to obtain a solidified product; (6) placing the solidified material obtained in step (5) into a waste incinerator for incineration to obtain slag; There is no order of precedence for steps (3) and (4) to (6).

2. The processing method according to claim 1, characterized in that: In the step (1), the ratio of the volume of the external drainage of the circulating cooling water of the waste incineration power plant to the mass of the fly ash is (2-8) mL: 1 g.

3. The processing method according to claim 1, characterized in that: The number of times of washing with water in the step (1) is 3 to 5 times.

4. The processing method according to claim 1, characterized in that: The water washing in step (1) is carried out under stirring conditions.

5. The processing method according to claim 1, characterized in that: The purification in step (2) comprises the following steps: 1) Adjusting the pH value of the high-salt water to 7.5-8.5, then mixing the high-salt water with water-soluble carbonate to carry out a precipitation reaction to obtain a high-salt water containing precipitation; 2) The high-salt water containing precipitates obtained in step 1) is mixed with a flocculant and flocculated to obtain purified high-salt water and second ash.

6. The processing method according to claim 5, characterized in that: In step 1), the pH value of the high-salt water is adjusted by aeration with carbon dioxide or by adding dilute hydrochloric acid.

7. The processing method according to claim 6, characterized in that: The rate of carbon dioxide aeration is 0.1-1.0 L / min.

8. The processing method according to claim 5, characterized in that: The precipitation reaction time in step 1) is 30 to 90 minutes.

9. The processing method according to claim 5, characterized in that: The mass of the flocculant in step 2) is 0.001-0.005% of the mass of the high-salt water containing the precipitate.

10. The processing method according to claim 1, characterized in that: The electrolysis in step (3) is intermittent electrolysis.

Images