CN110640080A - Waste water glass sand wet regeneration method without wastewater discharge - Google Patents
Waste water glass sand wet regeneration method without wastewater discharge Download PDFInfo
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- CN110640080A CN110640080A CN201910848944.7A CN201910848944A CN110640080A CN 110640080 A CN110640080 A CN 110640080A CN 201910848944 A CN201910848944 A CN 201910848944A CN 110640080 A CN110640080 A CN 110640080A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C5/00—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose
- B22C5/06—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose by sieving or magnetic separating
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- B22—CASTING; POWDER METALLURGY
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- B22C5/00—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose
- B22C5/04—Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose by grinding, blending, mixing, kneading, or stirring
- B22C5/0409—Blending, mixing, kneading or stirring; Methods therefor
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
- C02F1/5245—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents using basic salts, e.g. of aluminium and iron
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Abstract
The invention discloses a wet regeneration method of used sodium silicate sand without wastewater discharge, which comprises the following steps: (1) crushing and screening the used sodium silicate sand, mixing with clear water, and directly standing for 10-36 h; or mechanically stirring for 3-10min, separating sand from water to obtain wet sand and regeneration wastewater, and drying the wet sand to obtain regeneration sand; (2) adding alkaline inorganic powder into the regeneration wastewater, mixing and stirring, standing for precipitation, filtering to obtain clear liquid, and using the clear liquid for the wet regeneration water of the next batch of the used water glass sand. The invention uses three different inorganic alkaline powders of magnesium hydroxide, calcium hydroxide and calcium oxide to remove harmful components in the wet regeneration wastewater, the treated and filtered wastewater is recycled for the regeneration of the used sodium silicate sand, the performance of the regenerated sand is similar to that of the new sand, the process requirements can be completely met, the effect of calcium oxide treatment on the regeneration wastewater is best, the molar ratio of sodium carbonate to the alkaline inorganic powder in the wastewater is 1: 6.
Description
Technical Field
The invention belongs to the field of resource recycling in the casting industry, and particularly relates to a waste sodium silicate sand wet regeneration method without waste water discharge.
Background
Green clean production is the development trend of casting production, and in order to realize green clean production, the whole regeneration and reuse of used sand is the key. Sodium silicate sand is recognized as the molding sand most likely to realize green casting. The water glass sand is colorless, tasteless and nontoxic, does not produce irritant gas and toxic gas in the sand mixing, modeling pouring and shakeout processes and has no harm to human bodies, the greatest defect is that the water glass sand is difficult to regenerate and causes great pollution, so that the problem of recycling can be realized, and the water glass sand enters a green casting line and row first.
The wet regeneration of used sodium silicate sand is to remove residual binder, salt, ester and other water-soluble substances on the surface of used sand grains by utilizing the dissolving and scrubbing action of water and the mechanical stirring action. The wet-process reclaimed sodium silicate used sand has the advantages of high residual binder removal rate, good reclaimed sand quality and the like, a large amount of alkaline wastewater is generated after the existing sodium silicate used sand is regenerated by a wet process, the alkaline wastewater can be recycled or discharged outwards after being treated, and the problem of wastewater treatment is not well solved all the time.
The water glass sand sewage has the characteristics that: the water glass sand sewage generally contains more sodium carbonate, NaOH, silicic acid colloid and clay colloid. Both colloidal particles are negatively charged, and due to the action of electrostatic repulsion, the colloidal particles are prevented from colliding with each other and are aggregated into larger particles, and the larger particles exist in the water in a stable suspension state, so that the sewage cannot be clarified through natural sedimentation. Therefore, it is necessary to add a coagulant that neutralizes the charge of the colloid to destabilize the agglomeration, and a flocculant that promotes the formation of larger flocs of the destabilized particles. He Fu Qiang et al uses acid to neutralize, then adds polyaluminium chloride (PAC) and Polyacrylamide (PAM) flocculant to treat sewage, after treatment most of colloid in sewage is removed, after treatment the turbidity of water isThe temperature is reduced to 25 ℃, the turbidity is close to 1 ℃ of purified water, and the sewage cannot be distinguished by human eyes, but the sewage can be effectively treated by adopting the method, the consumed chemical reagent amount is large, the cost is high, in addition, in the treatment process, acid is added to treat corrosion-prone equipment, and organic components such as chloride ions, aluminum ions, polyacrylamide and the like are brought in after the treatment. Longwei et al further treat the sewage by adding acid to lower the pH value of the sewage to 7 and adding organic bentonite and polyaluminium chloride to obtain satisfactory treatment effect. However, the cost of the organic bentonite is higher, and the treatment period is longer. CN201510528118.6 invention discloses a CO2The treatment method of the hardened sodium silicate sand wet-process regeneration wastewater comprises the steps of treating the sodium silicate sand wet-process regeneration wastewater in the casting industry by adopting a method of fractional pH adjustment, coagulation aid, precipitation and sludge dehydration, treating the concentrated precipitated sludge by using a plate-and-frame filter press and then transporting the treated sludge to the outside, passing the raw water for the casting sodium silicate sand wet-process regeneration through a pH coarse adjustment tank and a pH fine adjustment tank, respectively adding a coagulant PAC and a coagulant aid PAM before and after a pump, passing the raw water through a sequencing batch flocculation precipitation concentration tank, stopping water inlet treatment for 2-3 hours, discharging supernatant, and pumping the concentrated sludge at the bottom of the tank to the plate-and-frame filter press by using the pump. However, the method for treating the regenerated wastewater has the defects of complex process operation, long treatment period, high treatment cost and the like.
For the above reasons, the present application has been made.
Disclosure of Invention
Aiming at the problems or defects in the prior art, the invention aims to provide a method for regenerating used sodium silicate sand by a wet method without wastewater discharge. The invention is characterized in that chemical reagents are added to treat the sewage generated by the wet regeneration of the used water glass sand, the regeneration of the used sand and the recycling of filtrate are realized, and the performance of the regenerated sand is superior to that of the traditional wet regenerated sand.
In order to achieve the above purpose of the present invention, the technical solution adopted by the present invention is as follows:
a wet regeneration method of used sodium silicate sand without wastewater discharge comprises the following steps:
(1) crushing and screening the collected used sodium silicate sand, mixing with clear water, and directly standing for 10-36 h; or mechanically stirring for 3-10 min; then separating sand from water to obtain wet sand and regeneration wastewater, and drying the wet sand to obtain regeneration sand;
(2) and (2) adding alkaline inorganic powder into the regeneration wastewater obtained in the step (1), mixing and stirring, standing for precipitation, filtering to obtain clear liquid, using the clear liquid in the wet regeneration water for the next batch of the used water glass sand, and repeating the step (1).
Further, the above technical solution further includes step (3): and (2) when the total alkali amount in the reclaimed sand obtained in the step (1) exceeds the standard, leaching the reclaimed sand with clear water, and then using the leaching solution obtained by leaching to supplement water for used sand regeneration.
Further, according to the technical scheme, a high-frequency vibrating screen machine is preferably adopted for screening the used water glass sand in the step (1), wherein the vibrating screen machine is used for enabling the used water glass sand with different particle sizes to pass through a single-layer or multi-layer screen surface with uniformly distributed holes for multiple times, and separation of coarse sand and fine sand is finally achieved.
Further, according to the technical scheme, the mass ratio of the used water glass sand to the clean water in the step (1) is 1: 2-10, more preferably 1: 3.
further, in the above technical solution, the standing time in the step (1) is preferably 24 hours.
Further, in the above technical solution, the alkaline inorganic powder in the step (2) is any one of magnesium hydroxide, calcium hydroxide and calcium oxide.
Preferably, in the above technical solution, the alkaline inorganic powder in the step (2) is preferably calcium oxide.
Further, according to the technical scheme, the molar ratio of the sodium carbonate to the alkaline inorganic powder in the regeneration wastewater obtained in the step (2) is 1: 1-6.
Preferably, in the above technical scheme, the molar ratio of sodium carbonate to alkaline inorganic powder in the regeneration wastewater in step (2) is 1: 6.
further, in the above technical scheme, the mixing and stirring time in the step (2) is not particularly limited as long as the purposes of uniform mixing and sufficient reaction are achieved. The mixing and stirring time is preferably 1 to 10min, more preferably 3 min.
Further, in the above technical scheme, the standing time in the step (2) is not more than 36h, and more preferably 24 h.
In order to remove carbonate and other substances in the regeneration wastewater and reduce adverse effects of harmful component accumulation on the regeneration performance of the used sand, measures must be taken to remove carbonate, silicate and other components in the regeneration wastewater, and no new harmful components are introduced. The invention adopts three different inorganic alkaline powders of CaO and Ca (OH)2、Mg(OH)2The reaction equation for treating the regeneration wastewater is shown as the following formula, and CO in the regeneration wastewater can be converted by the reaction3 2-And SiO3 2-And removing the precipitate after filtration to obtain a dilute alkali solution.
CaO+CO3 2-+H2O＝CaCO3↓+2OH-+H2O
CaO+SiO3 2-+H2O＝CaSiO3↓+2OH-+H2O
Ca(OH)2+CO3 2-+H2O＝CaCO3↓+2OH-+H2O
Ca(OH)2+SiO3 2-+H2O＝CaSiO3↓+2OH-+H2O
Mg(OH)2+CO3 2-+H2O＝MgCO3↓+2OH-+H2O
Mg(OH)2+SiO3 2-+H2O＝MgSiO3↓+2OH-+H2O
The formula I is shown.
Compared with the prior art, the water glass used sand wet regeneration method without wastewater discharge has the following beneficial effects:
according to the invention, three different inorganic alkaline powders of magnesium hydroxide, calcium hydroxide and calcium oxide are used to remove harmful components in the wet regeneration wastewater, the treated and filtered wastewater is recycled for regeneration of the used sodium silicate sand, the performance of the regenerated sand is similar to that of the new sand, and the process requirements can be completely met. Experiments and comparative analysis show that the effect of treating the regenerated wastewater by calcium oxide is best, and the wastewater after calcium oxide treatment and filtration is reused for wet-process regeneration of sodium silicate sand, so that the content of sodium carbonate in the obtained regenerated sand is obviously reduced, and the content of sodium carbonate has no influence on the performance of the regenerated sand.
Drawings
FIG. 1 is a schematic process flow diagram of a waste water glass sand wet regeneration method without wastewater discharge.
FIG. 2 is a graph showing a volume-versus-volume ratio of carbon dioxide gas generated by dropping the clear liquid obtained in examples 1 to 3 of the present invention with an acid.
FIG. 3 is a graph showing the volume-to-volume ratio of carbon dioxide gas generated by dropping the clear liquid obtained in examples 4 to 11 with an acid.
FIG. 4 is a graph comparing the results of the initial strength tests of the reclaimed sand obtained in example 7 and example 12 of the present invention and the new sand and used sand purchased in the market: wherein the ordinate is the initial strength in MPa.
FIG. 5 is a graph comparing the results of the final strength tests of the reclaimed sand obtained in example 7 and example 12 of the present invention with commercially available fresh sand and used sand; wherein the ordinate is the final strength in MPa.
FIG. 6 is a graph comparing the results of the collapsibility tests of the reclaimed sand obtained in example 7 and example 12 of the present invention and new sand and used sand purchased in the market; where the ordinate is the residual strength in MPa.
FIG. 7 is a graph comparing the results of the initial strength, final strength and collapsibility tests of the reclaimed sand obtained in example 13 of the present invention and new sand and used sand purchased in the market; wherein the ordinate is the strength in MPa.
FIG. 8 is a graph showing a volume-to-volume ratio of carbon dioxide gas generated by dropping the new sand, the used sand and the reclaimed sand obtained in example 13 with an acid; wherein the ordinate is volume in mL.
Detailed Description
The present invention will be described in further detail below with reference to examples. The present invention is implemented on the premise of the technology of the present invention, and the detailed embodiments and specific procedures are given to illustrate the inventive aspects of the present invention, but the scope of the present invention is not limited to the following embodiments.
Various modifications to the precise description of the invention will be readily apparent to those skilled in the art from the information contained herein without departing from the spirit and scope of the appended claims. It is to be understood that the scope of the invention is not limited to the procedures, properties, or components defined, as these embodiments, as well as others described, are intended to be merely illustrative of particular aspects of the invention. Indeed, various modifications of the embodiments of the invention which are obvious to those skilled in the art or related fields are intended to be covered by the scope of the appended claims.
For a better understanding of the invention, and not as a limitation on the scope thereof, all numbers expressing quantities, percentages, and other numerical values used in this application are to be understood as being modified in all instances by the term "about". Accordingly, unless expressly indicated otherwise, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained. At the very least, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
The physical and chemical properties of the three alkaline inorganic powder raw materials adopted by the invention are as follows:
magnesium hydroxide, white amorphous powder. The suspension of magnesium hydroxide in water is called magnesium hydroxide emulsion, abbreviated as magnesium emulsion, and the magnesium hydroxide is colorless hexagonal column crystal or white powder, is difficult to dissolve in water and alcohol, is soluble in dilute acid and ammonium salt solution, and the aqueous solution is alkalescent.
Calcium oxide has a chemical formula of CaO, is white powder, is hygroscopic, is soluble in sucrose, acids, and the like, and is often used as a filler material in production. Because calcium oxide can react with carbon dioxide in the air, sealing and drying are guaranteed during storage.
Calcium hydroxide (calcium hydroxide),inorganic compound of the formula Ca (OH)2Commonly known as slaked lime or slaked lime. Is a white powdery solid, and is added with water to form an upper layer and a lower layer, wherein the upper layer of water solution is called as clear lime water, and the lower layer of suspension is called as lime milk or lime slurry.
The used sand screening steps involved in the following examples of the invention are as follows: firstly, using a tray to load a proper amount of crushed used sand (not screened) for further treatment, adopting 20-mesh and 200-mesh sieves, stacking the 20-mesh and 200-mesh sieves from top to bottom in sequence, using an iron shovel to load a proper amount of unscreened used sand into the 20-mesh sieves, then putting the sieves on a vibrating screen machine together, opening the vibrating screen machine after placing the sieves, selecting a 10min gear, automatically stopping the vibrating screen machine after 10min to finish primary vibrating screen, discarding the used sand on the 20-mesh sieve, loading the sand in the 200-mesh sieve into a bag to be used as the sand for the method, repeating the steps for three to four times after finishing primary vibrating screen (carrying out multiple vibrating screen according to the used sand amount) to obtain enough sand samples for later use. The particle size distributions of the used and fresh sands are shown in table 1 below.
TABLE 1 particle size distribution (%)
| Sieve number (mesh) | 30 | 40 | 50 | 70 | 100 | 140 | 200 | >200 | Total amount of |
| Raw sand | 6.04 | 5.74 | 28.49 | 36.76 | 22.86 | 5.04 | 0.40 | 0.10 | 99.30 |
| Old sand after screening | 4.3 | 11.48 | 26.06 | 31.04 | 17.37 | 4.55 | 1.39 | 3.76 | 99.95 |
The water glass used in the following examples is native to Wuhan, has a modulus of 3.1 and a density of 1.32, and when used, a certain amount of saturated NaOH solution is added and mixed uniformly to adjust the modulus and density of the water glass, and after adjustment, the modulus M of the water glass is 2.3 and the density is 1.41. The adding amount accounts for 6.0 percent of the raw sand; the sand sample for the performance test is prepared on a hammering type sample making machine by adopting a hollow cylindrical sample barrel, and the diameter of the sand sample is 30mm, and the height of the sand sample is 30 mm.
Carbon dioxide gas for hardening water glass: adopt wuBottled industrial CO manufactured by Hantong company2And (3) blowing gas with the flow rate of 15L/min for 15-20 s.
Example 1
The method for regenerating the used sodium silicate sand without wastewater discharge by the wet method comprises the following steps:
(1) crushing and screening 500g of collected used sodium silicate sand, mixing with 1500g of clear water, mechanically stirring for 3min, separating sand from water after stirring to obtain wet sand and regeneration wastewater, and drying the wet sand to obtain regeneration sand;
(2) and (2) taking 100mL of the regenerated wastewater obtained in the step (1), adding 0.5g (excessive) of calcium oxide, mixing and stirring for 30s, standing and precipitating for 24h, and filtering to obtain a clear solution.
Example 2
The method for regenerating used sodium silicate sand without wastewater discharge in the embodiment is basically the same as the method in the embodiment 1, except that: in this example, 0.5g (excess) of calcium hydroxide was added in step (2).
Example 3
The method for regenerating used sodium silicate sand without wastewater discharge in the embodiment is basically the same as the method in the embodiment 1, except that: in this example, 0.5g (excess) of magnesium hydroxide was added in step (2).
CO in the regenerated wastewater and the clear liquid obtained in example 1 and the clear liquids obtained in examples 2 and 3 were measured by a gas method, respectively3 2-The content of (b) is measured by the volume of carbon dioxide gas generated by acid drop wastewater (or clear liquid). During measurement, 10mL of liquid is taken each time, and the average value of the gas volume is taken after each liquid is measured for three times. The results are shown in FIG. 2, in which: in the figure, raw liquor represents the wastewater obtained in example 1, and CaO represents the clear liquor obtained in example 2; ca (OH)2The clear liquid obtained in example 2 is shown; mg (OH)2The clear liquid obtained in example 3 is shown.
As can be seen from FIG. 2, in the wastewater treated with the same excess reagent, CaO and Ca (OH) are added2Gas produced by clear liquid obtained by treating regeneration wastewaterObviously reduces the amount of carbonate in the clear liquid, and has equivalent treatment effect, and Mg (OH)2The treatment effect of (a) is not significant compared with the former two effects, so that the inorganic alkaline powder of the present invention preferably employs calcium oxide and calcium hydroxide.
Example 4
The method for regenerating the used sodium silicate sand without wastewater discharge by the wet method comprises the following steps:
(1) crushing and screening 500g of collected used sodium silicate sand, mixing with 1500g of clear water, standing and precipitating for 24h, separating sand from water to obtain wet sand and regeneration wastewater, and drying the wet sand to obtain regeneration sand;
(2) and (2) adding calcium oxide into 100mL of the regenerated wastewater obtained in the step (1), mixing and stirring for 30s, standing for 24h, and filtering to obtain a clear solution, wherein: the molar ratio of sodium carbonate to calcium oxide in the regeneration wastewater is 1: 1.
example 5
The method for regenerating used sodium silicate sand without wastewater discharge in the embodiment is basically the same as the method in the embodiment 4, and only differs from the following steps: in this embodiment, the molar ratio of sodium carbonate to calcium oxide in the regeneration wastewater in step (2) is 1: 2.
example 6
The method for regenerating used sodium silicate sand without wastewater discharge in the embodiment is basically the same as the method in the embodiment 4, and only differs from the following steps: in this embodiment, the molar ratio of sodium carbonate to calcium oxide in the regeneration wastewater in step (2) is 1: 4.
example 7
The method for regenerating used sodium silicate sand without wastewater discharge in the embodiment is basically the same as the method in the embodiment 4, and only differs from the following steps: in this embodiment, the molar ratio of sodium carbonate to calcium oxide in the regeneration wastewater in step (2) is 1: 6.
example 8
The method for regenerating used sodium silicate sand without wastewater discharge in the embodiment is basically the same as the method in the embodiment 4, and only differs from the following steps: in this embodiment, the inorganic alkaline powder added in step (2) is calcium hydroxide, and the amount of the inorganic alkaline powder is the same as that of the calcium oxide in embodiment 4.
Example 9
The method for regenerating used sodium silicate sand without wastewater discharge in the embodiment is basically the same as the embodiment 5 except that: in this embodiment, the inorganic alkaline powder added in step (2) is calcium hydroxide, and the amount of the inorganic alkaline powder is the same as that of the calcium oxide in embodiment 5.
Example 10
The method for regenerating used sodium silicate sand without wastewater discharge in the embodiment is basically the same as the method in the embodiment 6, and only differs from the following steps: in this embodiment, the inorganic alkaline powder added in step (2) is calcium hydroxide, and the amount of the inorganic alkaline powder is the same as that of the calcium oxide in embodiment 6.
Example 11
The method for regenerating used sodium silicate sand without wastewater discharge in the embodiment is basically the same as the method in the embodiment 7, and only differs from the following steps: in this embodiment, the inorganic alkaline powder added in step (2) is calcium hydroxide, and the amount of the inorganic alkaline powder is the same as that of the calcium oxide in embodiment 7.
CO in the clear solutions obtained in examples 4 to 11 was measured by the gas method, respectively3 2-The content of (b) is measured by the volume of carbon dioxide gas generated by acid drop wastewater (or clear liquid). During measurement, 10mL of liquid is taken each time, and the average value of the gas volume is taken after each liquid is measured for three times. The results are shown in FIG. 3.
As can be seen from FIG. 3, Ca (OH)2Treating the resulting supernatant to produce CO2The volume decreases faster with increasing proportion than CaO, but the upper limit of CaO treatment is higher than Ca (OH)2High, namely the molar ratio of sodium carbonate to calcium oxide or calcium hydroxide in the regeneration wastewater is 1: when 6, CaO is more effective than Ca (OH)2Preferably, the Na in the sewage is completely removed or removed as much as possible2CO3The present invention optimally selects CaO as a treatment agent for wastewater to be regenerated, and uses 1:6 to process.
In order to test the treatment effect of the clear liquid obtained by the present invention for the wet regeneration treatment of used water glass sand, the following examples were set.
Example 12
500g of collected used sodium silicate sand is crushed and sieved and then mixed with 1500g of clear liquid obtained in example 7, the mixture is mechanically stirred for 3min, standing and precipitating for 24h after stirring is finished, then sand and water are separated to obtain wet sand and regeneration wastewater, and the wet sand is dried to obtain regeneration sand.
The reclaimed sand obtained in example 7 and example 12, respectively, and the new sand and used sand purchased in the market were tested for initial strength, final strength, and collapsibility.
Wherein: the initial strength and final strength test method is as follows:
weighing 1.0kg of sand sample by using an electronic balance, putting the sand sample into a stirring pot, then using a micropipette to take 60g of water glass, pouring the water glass into the stirring pot, correctly placing the stirring pot on a cement-cement sand stirring machine, turning on a switch to select a low speed gear, stirring for three minutes, and taking down the stirring pot after the stirring is finished. Using a hammer type sampling machine to prepare samples, weighing 33g of mixed sand samples by using an electronic balance each time, and using 15ml/min of CO2Blowing for 20 seconds to play a hardening role, taking out a sample after blowing, and measuring the in-time (initial) strength of the three samples (sample 1, sample 2 and sample 3) after continuously preparing the same samples by using a hydraulic universal strength tester. And (4) preparing a sample by adopting the steps, and placing the sample preparation tray for 24 hours. After 24 hours, the final strength was measured by a hydraulic universal strength tester.
Collapsibility test method is as follows: opening a high-temperature box type resistance furnace in advance, preheating for about two hours, and enabling the temperature in the furnace to reach 800 ℃. When the temperature reaches the requirement, iron sheets are used for placing and preparing samples, iron tongs are used for placing the samples into a high-temperature box type resistance furnace, the furnace door is closed, and the furnace is kept heated for 20 minutes at 800 ℃. And after the time is reached, taking out the prepared sample, naturally cooling the prepared sample, and measuring the strength of the prepared sample at normal temperature by using a hydraulic universal strength tester to obtain collapsibility.
The test results of the initial strength of the reclaimed sand obtained in example 7 and the reclaimed sand obtained in example 12, and the new sand and the used sand purchased in the market are shown in fig. 4. As can be seen from FIG. 4Waste sand directly water glass CO2The initial strength after blow hardening was the highest, and the regenerated used sand obtained in example 7 had a slightly lower initial strength than the used sand, but a higher initial strength than the fresh sand and the regenerated sand obtained in example 12, while the regenerated sand obtained in example 12 had a slightly higher initial strength than the fresh sand, approaching the properties of the fresh sand.
The test results of the final strength of the reclaimed sand obtained in example 7 and the test results of the reclaimed sand obtained in example 12, and the new sand and the used sand purchased in the market are shown in fig. 5. Fig. 5 was obtained. As can be seen from FIG. 5, CO of the reclaimed used sand obtained in example 7 added with water glass2The final strength after blow hardening is slightly lower than that of the used sand, the new sand and the regenerated used sand obtained in example 12 are both obviously lower than that of the used sand, the strength of the new sand is the lowest, and the regenerated used sand obtained in example 12 is similar to that of the new sand.
The results of the collapsibility tests of the reclaimed sand obtained in example 7 and the reclaimed sand obtained in example 12, and the new sand and the used sand purchased in the market are shown in fig. 6. As can be seen from fig. 6, the used sand has the highest residual strength, the regenerated used sand obtained in example 7 has the lowest residual strength, and the new sand has a residual strength close to that of the regenerated used sand obtained in example 12.
According to the performance test results of the reclaimed sand, the reclaimed sand obtained by the method and the clear liquid obtained by calcium oxide treatment and filtration are reused for wet regeneration of the used sodium silicate sand are relatively close to the new sand in the three performance indexes of initial strength, final strength and residual strength, and the reclaimed sand treated by adding the calcium oxide in a ratio of 1:6 meets the performance requirements.
When regenerating used sand, the total alkali content in the regenerated sand is a standard for measuring the regeneration effect. Therefore, the invention also measures the total alkali amount and the sodium carbonate content of the reclaimed sand obtained in example 7 and example 12 respectively and the sand sample filtrate of the new sand and the used sand purchased in the market.
The method for testing the total alkali content and the sodium carbonate content in the purchased used sand sample comprises the following steps:
the total alkali content test method is as follows:
cleaning 100g of used sand, suction-filtering with SHB-III circulating water type multipurpose vacuum pump, centrifuging the obtained filtrate at 7000r/min for 7 min, and adding into volumetric flask to constant volume to obtain the final extract. 10ml (about 10g) of the extract was taken for total alkali amount measurement, three to four drops of bromocresol green-methyl red indicator were added dropwise, shaking was conducted, and the solution was blue. And (2) titrating hydrochloric acid by using an acid burette, marking an initial scale before titration, stopping titration when the solution is changed from blue to red, marking a termination scale, calculating the volume of the consumed hydrochloric acid from the initial scale and the termination scale to finish one measurement, sequentially measuring for three times by adopting the steps, and obtaining the initial scale, the termination scale and the dosage test results as shown in the following table 2.
TABLE 2 Tertiary acid-base titration test results table
Note: the concentration of the hydrochloric acid used was 0.064 mol/L.
That is, the average amount of hydrochloric acid used was (21.1+21+20.9)/3 ═ 21ml, and the total alkali amount was calculated according to the following calculation formula:
wherein: c-concentration of hydrochloric acid used (mol/L);
v1 — volume of hydrochloric acid used (ml);
m represents the mass (g) of the sample.
The method for measuring the content of sodium carbonate comprises the following steps:
taking 10ml (about 10g) of the extracting solution, putting the extracting solution into a round-bottom flask, dripping 2-3 drops of methyl red indicator (yellow), putting the extracting solution on a constant-temperature magnetic stirrer (putting a magnet into the flask), turning on a power supply after a gas volume method measuring device is correctly installed, firstly recording an initial scale of a gas measuring pipe, adjusting a switch of a nearby U-shaped gas measuring pipe while dripping hydrochloric acid, stopping dripping the hydrochloric acid when the solution in the round-bottom flask becomes red, and recording a termination scale when liquid levels at two sides in the U-shaped pipe are in phase. The above procedure was carried out three times in succession, and the data obtained are shown in Table 3 below.
TABLE 3 Tertiary acid-base titration test results table
Note: the concentration of the hydrochloric acid is 0.064mol/L
Average CO2The volume is as follows: (13.5+13.2+13.6)/3 ═ 13.43ml, and the sodium carbonate content was roughly calculated according to the following formula:
wherein: v, producing the volume (the liquid level descending volume of the U-shaped pipe) ml of carbon dioxide;
m-mass (g) of the sample taken.
The total alkali content and the sodium carbonate content of the reclaimed sand respectively obtained in example 7 and example 12 of the present invention were measured by the same method as the total alkali content test of the used sand sample, and the test results are shown in tables 4 and 5.
Table 4 used sand, example 7, and example 12 total alkali test results table
Table 5 used sand, example 7, and example 12 reclaimed sand test results of sodium carbonate content
As can be seen from table 4, the total alkali amount of the reclaimed sand obtained in example 12 is lower than that of the reclaimed used sand obtained in example 7; as can be seen from table 5, the content of sodium carbonate in the reclaimed sand fraction obtained in example 12 was lower than that in the reclaimed used sand obtained in example 7.
By the comparison of the above performance tests, the reclaimed sand obtained in example 12 satisfies the requirements in terms of initial strength, final strength, pot life, collapsibility, and the like. From the above comparative experiments of harmful components, it was found that the sodium carbonate content of the reclaimed sand obtained in example 12 was the least, and therefore the reclaimed sand obtained by recycling the clear liquid obtained by the wet reclamation of the present invention to the wet reclamation of the water glass sand satisfied the process requirements.
Example 13
1) Mixing 88.25g of calcium oxide and 170.19g of water to prepare lime slurry, and sealing for later use;
2) selecting 1500g of used sand, measuring the sodium carbonate content of the used sand to be 2.6%, adding 3000ml of tap water, stirring for 5min for wet regeneration, filtering and separating the regenerated sand from regenerated wastewater, washing the regenerated sand with 600ml of clear water, and drying to obtain 500ml of washing liquid; adding water glass mixed sand into the reclaimed sand to prepare a sample, and testing the performance of the reclaimed sand (directly reclaimed sand);
3) adding the lime slurry prepared in the step 1) into 2400g of sewage, mixing, stirring for 30s, and standing for 1min to obtain sewage treatment liquid;
4) selecting 1000g of used sand, washing 2000ml of treatment solution of the supernatant of the sewage treatment solution obtained in the step 3) and adding the treatment solution into the used sand, stirring for 5min for wet regeneration, filtering and separating regenerated sand and regenerated wastewater, drying the regenerated sand, adding water glass mixed sand for sample preparation, and testing the performance of the regenerated sand (secondary regenerated sand);
5) selecting 1000g of used sand, taking 1500ml of treatment fluid of the supernatant fluid of the sewage treatment fluid obtained in the step 4), stirring for 5min for wet regeneration, filtering and separating regenerated sand and regenerated wastewater, drying the regenerated sand, adding water glass sand mixture for sample preparation, and testing the performance of the regenerated sand (three times of regenerated sand);
in order to compare the regeneration effect, new sand and old sand of the same kind of original sand are adopted, and the same amount of water glass and the same sample preparation and blowing process are added, so that the performances of the molding sand are measured as shown in table 6:
TABLE 6 comparison of New, used and reclaimed sands for Performance
The test results shown in table 6, fig. 7 and fig. 8 indicate that: the addition amount of calcium oxide, the addition amount of water and the standing time have different influences on the regeneration effect in the regeneration process, and the final strength is enhanced and the collapsibility is poor along with the increase of the addition amount of water in a certain range; the addition amount of the calcium oxide is not too low or too high, and the standing treatment time is preferably 12 h. After appropriate regeneration treatment, the performance of the regenerated sand is close to that of new sand, the final strength even exceeds that of the new sand, the content of residual sodium carbonate in the sand after repeated regeneration is obviously reduced, the content is close to that of direct regenerated sand, 90% of sodium carbonate in old sand is removed, the regeneration process removes and activates residual water glass in the old sand, the bonding performance of the residual water glass is recovered, the strength and other properties of the regenerated sand exceed that of the new sand, therefore, the addition of the water glass during the production of the regenerated sand can be reduced, and the regeneration recycling rate of the old sand can reach 85-95%; and when the sand is regenerated for multiple times, the regenerated liquid is reduced, if sand washing water is not supplemented, the initial strength of the regenerated sand is lower than that of new sand, the final strength and the residual strength of the regenerated sand are higher than those of the new sand, and water needs to be supplemented properly during sand washing.
Claims (9)
1. A wet regeneration method of used sodium silicate sand without wastewater discharge is characterized in that: the method specifically comprises the following steps:
(1) crushing and screening the collected used sodium silicate sand, mixing with clear water, and directly standing for 10-36 h; or mechanically stirring for 3-10 min; then separating sand from water to obtain wet sand and regeneration wastewater, and drying the wet sand to obtain regeneration sand;
(2) and (2) adding alkaline inorganic powder into the regeneration wastewater obtained in the step (1), mixing and stirring, standing for precipitation, filtering to obtain clear liquid, using the clear liquid in the wet regeneration water for the next batch of the used water glass sand, and repeating the step (1).
2. The wet regeneration method of used sodium silicate sand without wastewater discharge according to claim 1, characterized in that: further comprising the step (3): and (2) when the total alkali amount in the reclaimed sand obtained in the step (1) exceeds the standard, leaching the reclaimed sand with clear water, and then using leaching liquid obtained by leaching to supplement water for used sand regeneration.
3. The wet regeneration method of used sodium silicate sand without wastewater discharge according to claim 1, characterized in that: the mass ratio of the used water glass sand to the clear water in the step (1) is 1: 2-10.
4. The wet regeneration method of used sodium silicate sand without wastewater discharge according to claim 1, characterized in that: and (3) the alkaline inorganic powder in the step (2) is any one of magnesium hydroxide, calcium hydroxide and calcium oxide.
5. The wet regeneration method of used sodium silicate sand without wastewater discharge according to claim 4, characterized in that: the alkaline inorganic powder in the step (2) is preferably calcium oxide.
6. The wet regeneration method of used sodium silicate sand without wastewater discharge according to claim 1, characterized in that: the molar ratio of the alkaline inorganic powder in the step (2) to the sodium carbonate in the regeneration wastewater is 1-6: 1.
7. the wet regeneration method of used sodium silicate sand without wastewater discharge according to claim 5, characterized in that: the mol ratio of the calcium oxide to the sodium carbonate in the regeneration wastewater in the step (2) is 6: 1.
8. the wet regeneration method of used sodium silicate sand without wastewater discharge according to claim 1, characterized in that: and (3) mixing and stirring time of the step (2) is 1-10 min.
9. The wet regeneration method of used sodium silicate sand without wastewater discharge according to claim 1, characterized in that: the standing time in the step (2) is not more than 36 h.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113245506A (en) * | 2021-04-25 | 2021-08-13 | 燕山大学 | Method for regenerating sodium silicate sand by using carbide slag |
Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1312219A (en) * | 2001-01-17 | 2001-09-12 | 上海交通大学 | Chemical restoring process of CO2 hardened old water glass sand |
| JP2004113102A (en) * | 2002-09-26 | 2004-04-15 | Takehiko Oki | Molding such as cultivation vessel |
| CN101869965A (en) * | 2010-06-21 | 2010-10-27 | 余钟泉 | Method for recycling cast waste sand |
| CN102974757A (en) * | 2012-12-12 | 2013-03-20 | 武汉纺织大学 | Combined treatment method for used water glass sand reclamation and reclamation treating liquid concentration |
| CN103394638A (en) * | 2013-08-20 | 2013-11-20 | 武汉纺织大学 | Method and apparatus for backwashing and regenerating casting used sand |
| CN104399877A (en) * | 2014-11-11 | 2015-03-11 | 天津众智科技有限公司 | Method utilizing microwaves to regenerate used sodium silicate sand |
| CN104399876A (en) * | 2014-11-11 | 2015-03-11 | 天津众智科技有限公司 | Method utilizing ultrasonic technology to regenerate used sodium silicate sand |
| CN104759584A (en) * | 2015-04-22 | 2015-07-08 | 莒州集团有限公司 | Water glass waste sand regeneration optimizing treatment method and water glass waste sand regeneration optimizing treatment system |
| CN109399652A (en) * | 2018-10-19 | 2019-03-01 | 华中科技大学 | A method of recycling waterglass from used sodium silicate sand wet reclamation sewage |
| CN109967693A (en) * | 2019-05-06 | 2019-07-05 | 北京仁创砂业科技有限公司 | The method for removing the additive of cast used sand inert coating and removing cast used sand inert coating |
| CN110125329A (en) * | 2019-05-31 | 2019-08-16 | 南阳仁创砂业科技有限公司 | A kind of regeneration method of used sodium silicate sand |
| CN110405136A (en) * | 2019-09-04 | 2019-11-05 | 北京仁创砂业铸造材料有限公司 | A kind of the wet reclamation additive and regeneration method of silicate cast used sand |
-
2019
- 2019-09-09 CN CN201910848944.7A patent/CN110640080A/en active Pending
Patent Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1312219A (en) * | 2001-01-17 | 2001-09-12 | 上海交通大学 | Chemical restoring process of CO2 hardened old water glass sand |
| JP2004113102A (en) * | 2002-09-26 | 2004-04-15 | Takehiko Oki | Molding such as cultivation vessel |
| CN101869965A (en) * | 2010-06-21 | 2010-10-27 | 余钟泉 | Method for recycling cast waste sand |
| CN102974757A (en) * | 2012-12-12 | 2013-03-20 | 武汉纺织大学 | Combined treatment method for used water glass sand reclamation and reclamation treating liquid concentration |
| CN103394638A (en) * | 2013-08-20 | 2013-11-20 | 武汉纺织大学 | Method and apparatus for backwashing and regenerating casting used sand |
| CN104399877A (en) * | 2014-11-11 | 2015-03-11 | 天津众智科技有限公司 | Method utilizing microwaves to regenerate used sodium silicate sand |
| CN104399876A (en) * | 2014-11-11 | 2015-03-11 | 天津众智科技有限公司 | Method utilizing ultrasonic technology to regenerate used sodium silicate sand |
| CN104759584A (en) * | 2015-04-22 | 2015-07-08 | 莒州集团有限公司 | Water glass waste sand regeneration optimizing treatment method and water glass waste sand regeneration optimizing treatment system |
| CN109399652A (en) * | 2018-10-19 | 2019-03-01 | 华中科技大学 | A method of recycling waterglass from used sodium silicate sand wet reclamation sewage |
| CN109967693A (en) * | 2019-05-06 | 2019-07-05 | 北京仁创砂业科技有限公司 | The method for removing the additive of cast used sand inert coating and removing cast used sand inert coating |
| CN110125329A (en) * | 2019-05-31 | 2019-08-16 | 南阳仁创砂业科技有限公司 | A kind of regeneration method of used sodium silicate sand |
| CN110405136A (en) * | 2019-09-04 | 2019-11-05 | 北京仁创砂业铸造材料有限公司 | A kind of the wet reclamation additive and regeneration method of silicate cast used sand |
Non-Patent Citations (1)
| Title |
|---|
| 卢记军等: ""水玻璃旧砂再生研究现状及展望"", 《铸造设备与工艺》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113245506A (en) * | 2021-04-25 | 2021-08-13 | 燕山大学 | Method for regenerating sodium silicate sand by using carbide slag |
| CN113245506B (en) * | 2021-04-25 | 2022-05-10 | 燕山大学 | Method for regenerating sodium silicate sand by using carbide slag |
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