CN114406187A - Regeneration method of waste water glass casting sand, regenerated sand and casting mold - Google Patents
Regeneration method of waste water glass casting sand, regenerated sand and casting mold Download PDFInfo
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- CN114406187A CN114406187A CN202210100429.2A CN202210100429A CN114406187A CN 114406187 A CN114406187 A CN 114406187A CN 202210100429 A CN202210100429 A CN 202210100429A CN 114406187 A CN114406187 A CN 114406187A
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- 239000004576 sand Substances 0.000 title claims abstract description 145
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 title claims abstract description 75
- 235000019353 potassium silicate Nutrition 0.000 title claims abstract description 70
- 238000007527 glass casting Methods 0.000 title claims abstract description 36
- 238000011069 regeneration method Methods 0.000 title claims abstract description 27
- 238000005266 casting Methods 0.000 title abstract description 12
- 239000002351 wastewater Substances 0.000 title abstract description 8
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims abstract description 87
- 239000007864 aqueous solution Substances 0.000 claims abstract description 81
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims abstract description 42
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 claims abstract description 38
- 238000000034 method Methods 0.000 claims abstract description 34
- 235000006408 oxalic acid Nutrition 0.000 claims abstract description 26
- 235000019270 ammonium chloride Nutrition 0.000 claims abstract description 21
- 229910001629 magnesium chloride Inorganic materials 0.000 claims abstract description 19
- 238000001035 drying Methods 0.000 claims abstract description 18
- 239000002244 precipitate Substances 0.000 claims abstract description 18
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 claims abstract description 14
- 239000001110 calcium chloride Substances 0.000 claims abstract description 14
- 229910001628 calcium chloride Inorganic materials 0.000 claims abstract description 14
- 239000002699 waste material Substances 0.000 claims description 42
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 20
- 238000003756 stirring Methods 0.000 claims description 20
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 10
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 10
- 235000017550 sodium carbonate Nutrition 0.000 claims description 10
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 7
- 239000000920 calcium hydroxide Substances 0.000 claims description 7
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 7
- 235000011116 calcium hydroxide Nutrition 0.000 claims description 6
- 150000002148 esters Chemical class 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 6
- 239000001569 carbon dioxide Substances 0.000 claims description 5
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- 150000007524 organic acids Chemical class 0.000 abstract description 2
- 230000001172 regenerating effect Effects 0.000 abstract description 2
- 235000005985 organic acids Nutrition 0.000 abstract 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 118
- 229960002337 magnesium chloride Drugs 0.000 description 13
- 229960002713 calcium chloride Drugs 0.000 description 9
- 229910052911 sodium silicate Inorganic materials 0.000 description 8
- 239000004115 Sodium Silicate Substances 0.000 description 7
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- 229940050906 magnesium chloride hexahydrate Drugs 0.000 description 6
- DHRRIBDTHFBPNG-UHFFFAOYSA-L magnesium dichloride hexahydrate Chemical compound O.O.O.O.O.O.[Mg+2].[Cl-].[Cl-] DHRRIBDTHFBPNG-UHFFFAOYSA-L 0.000 description 6
- 239000003110 molding sand Substances 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 230000008929 regeneration Effects 0.000 description 5
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- 230000000704 physical effect Effects 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 229940063656 aluminum chloride Drugs 0.000 description 2
- 229960001040 ammonium chloride Drugs 0.000 description 2
- LLSDKQJKOVVTOJ-UHFFFAOYSA-L calcium chloride dihydrate Chemical compound O.O.[Cl-].[Cl-].[Ca+2] LLSDKQJKOVVTOJ-UHFFFAOYSA-L 0.000 description 2
- 229940052299 calcium chloride dihydrate Drugs 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 150000004965 peroxy acids Chemical class 0.000 description 2
- 239000004848 polyfunctional curative Substances 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 238000007528 sand casting Methods 0.000 description 2
- -1 sand water glass ester Chemical class 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 1
- 229910020101 MgC2 Inorganic materials 0.000 description 1
- 206010028813 Nausea Diseases 0.000 description 1
- 239000006004 Quartz sand Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000002738 chelating agent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 208000002173 dizziness Diseases 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 1
- 239000000347 magnesium hydroxide Substances 0.000 description 1
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 230000008693 nausea Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 239000002602 strong irritant Substances 0.000 description 1
- 208000024891 symptom Diseases 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
Classifications
-
- 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
- B22C5/04—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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
- B22C1/02—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/02—Sand moulds or like moulds for shaped castings
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Glass Melting And Manufacturing (AREA)
Abstract
The invention belongs to the technical field of water glass sand, and particularly relates to a regeneration method of waste water glass casting sand, regenerated sand and a casting mold, which comprises the steps of respectively adding ammonium chloride, calcium chloride and/or magnesium chloride into an aqueous solution containing the waste water glass casting sand to reduce the modulus of high-modulus water glass in the waste water glass casting sand; and continuously adding oxalic acid until no white precipitate is generated in the aqueous solution, and dehydrating and drying to obtain the reclaimed sand. The reclaimed sand prepared by the method for regenerating the waste water glass casting sand provided by the invention has the strength and collapsibility equivalent to those of new sand, and has better loose property and fluidity compared with reclaimed sand prepared without adding oxalic acid or other organic acids.
Description
Technical Field
The invention belongs to the technical field of water glass sand, and particularly relates to a regeneration method of water glass casting waste sand, regenerated sand and a casting mold.
Background
A large amount of used sodium silicate sand exists in the sodium silicate sand casting process, the reclaimed sand recovered by modifying the sodium silicate sand by a conventional method has obvious differences from natural sand in various properties, and other negative effects exist in the using process of the reclaimed sand, so that the reclaimed sand is still strongly resisted when being reused. For example, example 1: the waste sand produced when the sand mold is manufactured by the quartz sand water glass carbon dioxide hardening process is used, and the waste sand is subjected to conventional modification process, namely, the waste sand is soaked in 8% ammonium chloride solution and then dried for regeneration, the specific process is disclosed in the patent with the publication number of CN111331071A, the regenerated sand regenerated by the process is subjected to sand mixing by a single-arm water glass automatic sand mixer, strong irritant malodor is accompanied when the sand is discharged, and symptoms such as dizziness, nausea and the like of an operator are often caused. Among them, strong offensive odor is generated by the reaction formula that ammonium chloride remaining on the surface of reclaimed sand undergoes a double decomposition reaction with water glass during the sand mulling process to generate ammonia gas having offensive odor.
2NH4Cl+Na2SiO3＝2NaCl+SiO2↓+H2O+2NH3↑
Meanwhile, after the reclaimed sand is mixed with the water glass, under the condition that carbon dioxide is not introduced, the molding sand is rapidly dried and embrittled, namely the usable time of the prepared reclaimed sand is short, so that the problem that the compressive strength is remarkably reduced when the sand mold is prepared by using the molding sand is caused, particularly, the initial compressive strength of the sand mold prepared by using the molding sand is less than 0.1MPa, and the final compressive strength of the sand mold is less than 2.0MPa, so that the serious sand washing phenomenon exists in the actual gradual pouring process.
As another example, example 2: the waste sand produced in the process of manufacturing the sand mould by using the sea sand water glass ester hardening process is repeatedly used, and the surface of the waste sand is coated with a thicker water glass film, andthe residual quantity of Na2O is high, so 5% concentration aluminum chloride solution is adopted for soaking, stirring and drying regeneration, and the specific process is shown in the patent with the publication number CN111482554A, although Na in the regenerated sand obtained by regeneration2The content of O is obviously reduced, but the reclaimed sand obtained by the reclamation still has the following differences from the new sand:
firstly, after the reclaimed sand is mixed with water glass, the reclaimed sand becomes brittle and becomes dry without adding an ester hardener, so that the compression strength and the bonding strength of molding sand prepared by mixing the reclaimed sand which becomes brittle and becomes dry with the ester hardener are insufficient, and the molding sand cannot be used for manufacturing sand molds;
secondly, if the reclaimed sand is mixed with water glass before the phenomenon of brittleness and drying occurs, and an ester hardening agent is quickly mixed, although the prepared sand mold has enough compressive strength, the residual strength is high, the sand cleaning is difficult, and mechanical sand sticking is easily caused, so that the sand mold is not suitable for manufacturing a loam core with high requirements on refractoriness and collapsibility.
Therefore, a regeneration process capable of effectively improving the physical properties of the reclaimed sand is needed in the existing sodium silicate sand casting industry.
Disclosure of Invention
In order to overcome the defects of the prior art, the technical problems to be solved by the invention are as follows: provides a regeneration method of waste sodium silicate casting sand capable of effectively improving the physical properties of the regenerated sand, the regenerated sand prepared by the regeneration method and a casting mould consisting of the regenerated sand.
In order to solve the technical problems, the invention provides a regeneration method of water glass casting waste sand, which comprises the steps of respectively adding ammonium chloride, calcium chloride and/or magnesium chloride into an aqueous solution containing the water glass casting waste sand so as to reduce the high-modulus water glass modulus in the water glass casting waste sand;
and continuously adding oxalic acid until no white precipitate is generated in the aqueous solution, and dehydrating and drying to obtain the reclaimed sand.
Further provides reclaimed sand prepared by the method for reclaiming the waste sodium silicate casting sand.
Still further provided is a casting mold comprising water glass and the reclaimed sand.
The invention has the beneficial effects that: ammonium chloride, calcium chloride and/or magnesium chloride are respectively added into the aqueous solution containing the water glass casting waste sand to reduce the modulus of high-modulus water glass in the water glass casting waste sand, so that the demolding rate and the recovery rate of the reclaimed sand are effectively improved. Meanwhile, the pH value of the solution is controlled to avoid the generation of foul smell in the subsequent regeneration step and the use process of the regenerated sand due to the excessive addition of ammonium chloride. Furthermore, the oxalic acid is further added, so that the bonding strength (bonding strength/compressive strength) of the reclaimed sand prepared by the reclaiming method and the water glass can be further improved while the oxalic acid reacts with the residual magnesium chloride in the aqueous solution, and the obtained reclaimed sand is looser and has better fluidity compared with the existing reclaiming process, thereby further improving the performance of the reclaimed sand.
Detailed Description
In order to explain the technical content, the objects and the effects of the present invention in detail, the following description will be given with reference to the embodiments.
A regeneration method of water glass casting waste sand comprises the steps of respectively adding ammonium chloride, calcium chloride and/or magnesium chloride into an aqueous solution containing the water glass casting waste sand to reduce the high-modulus water glass modulus in the water glass casting waste sand;
and continuously adding oxalic acid until no white precipitate is generated in the aqueous solution, and dehydrating and drying to obtain the reclaimed sand.
Wherein, the reaction equation of adding ammonium chloride and magnesium chloride to react to reduce the high modulus water glass modulus in the waste sand of water glass casting is shown as follows.
Na2O·mSiO2·nH2O+2NH4Cl→mSiO2+2NaCl+2NH3↑+(n+1)H2O (1)；
Na2O·mSiO2·nH2O+CaCl2→mSiO2+2NaCl+Ca(OH)2+(n-1)H2O (2)；
Na2O·mSiO2·nH2O+MgCl2→mSiO2+2NaCl+Mg(OH)2+(n-1)H2O (3)；
And the reaction equation for the reaction by adding oxalic acid is shown below.
H2C2O4+MgCl2＝MgC2O4↓+2HCl (4)；
The reaction shown by the equations (1), (2) and (3) can effectively reduce the modulus of high-modulus water glass in the waste water glass casting sand, thereby improving the re-bonding strength of the reclaimed sand and prolonging the service life of the reclaimed sand, and avoiding the situations of rapid drying and embrittlement of the molding sand and the like. And, by further adding oxalic acid (see equation 4), the bonding strength (bonding strength/compressive strength) and collapsibility (residual strength) of the reclaimed sand to the water glass can be effectively improved while the oxalic acid reacts with the magnesium chloride remaining in the aqueous solution. Meanwhile, the inventor found in practical practice that the reclaimed sand regenerated by adding oxalic acid is looser, the compressive strength is remarkably improved and the residual strength is remarkably reduced compared with the reclaimed sand regenerated without adding oxalic acid or adding other organic acid, which may be related to the fact that oxalate (ox) is a chelating agent itself or can change the electrochemical properties of the surface of the reclaimed sand, and the reclaimed sand becomes looser by weakening the attraction among reclaimed sand particles.
In the present specification, the "phenomenon of becoming dry and brittle" refers to the phenomenon that the water glass is modified by residual ammonium chloride, aluminum chloride, calcium chloride or magnesium chloride, that is, the water glass is modified into amorphous silica by residual ammonium chloride, aluminum chloride, calcium chloride or magnesium chloride, so that the water glass loses the original properties and becomes dry and brittle.
Specifically, the regeneration method of the water glass casting waste sand comprises the following steps:
s1, mixing the water glass casting waste sand with water according to the mass ratio of 1: 0.3-1.2 to obtain the aqueous solution;
s2, continuously stirring the aqueous solution, adding ammonium chloride into the aqueous solution until the pH value of the aqueous solution is 12-13, and stopping adding the ammonium chloride;
s3, continuously adding calcium chloride and/or magnesium chloride into the aqueous solution until no white precipitate is generated in the aqueous solution, stopping adding the calcium chloride and/or the magnesium chloride, and continuously stirring the aqueous solution;
and S4, continuously adding oxalic acid into the aqueous solution until no white precipitate is generated in the aqueous solution, stopping adding oxalic acid, and dehydrating and drying the aqueous solution to obtain reclaimed sand.
It should be noted that the aqueous solution is continuously stirred in steps S2 to S4 and the subsequent step S5, and the stirring speed of the continuous stirring is preferably 20 to 200 rpm.
As shown in equation (4), hydrochloric acid is generated during the reaction of oxalic acid with magnesium chloride to cause the aqueous solution to be strongly acidic. Therefore, in order to avoid the aqueous solution peracid from corroding production equipment and avoid the aqueous solution of peracid from generating acid mist to pollute the surrounding environment in the drying process, the method preferably further comprises the steps of S5, continuing to add soda ash or slaked lime into the aqueous solution until the pH value of the aqueous solution is 6-7, stopping adding soda ash or slaked lime, and dehydrating and drying the aqueous solution to obtain the reclaimed sand after oxalic acid addition is stopped. I.e. by continuing to add soda ash or slaked lime to the aqueous solution after the addition of oxalic acid is stopped to neutralize the aqueous solution.
Preferably, in S3, the stirring time for continuously stirring the aqueous solution is 30 to 40 min. More preferably, the stirring time is 30 min.
Preferably, the drying condition is that the drying temperature is 50-200 ℃.
Wherein the water glass foundry waste sand is selected from waste sand produced by a carbon dioxide hardening process or an ester hardening process.
The reclaimed sand is prepared by the method for regenerating the waste water glass casting sand.
A casting mould comprising water glass and reclaimed sand as described above.
Example 1
A regeneration method of water glass casting waste sand comprises the following steps:
s1, stirring and mixing water glass casting waste sand generated in a carbon dioxide hardening process and water according to the mass ratio of 1:1 to obtain an aqueous solution, and detecting that the pH value of the aqueous solution exceeds 14 by using a pH test paper;
s2, continuously stirring the aqueous solution at a stirring speed of 20rpm/min, adding ammonium chloride powder into the aqueous solution until the pH value of the aqueous solution is 12, and stopping adding the ammonium chloride powder;
s3, continuously adding flaky magnesium chloride hexahydrate into the aqueous solution, wherein the aqueous solution quickly generates white precipitates, continuously adding flaky magnesium chloride hexahydrate till the aqueous solution does not generate white precipitates any more, stopping adding flaky magnesium chloride hexahydrate, and continuously stirring for 30 min;
s4, continuously adding oxalic acid powder into the aqueous solution after 30min, wherein white precipitate is rapidly generated in the aqueous solution, continuously adding oxalic acid powder until the white precipitate is not generated in the aqueous solution, and stopping adding oxalic acid powder, wherein the pH value of the aqueous solution is 2-3;
s5, continuing to add the soda ash into the aqueous solution, generating a large amount of bubbles in the aqueous solution, continuously adding the soda ash until the pH value of the aqueous solution is 6-7, and stopping adding the soda ash;
and S6, dehydrating the treated aqueous solution and drying at 100 ℃ to obtain the reclaimed sand.
Example 2
A regeneration method of water glass casting waste sand comprises the following steps:
s1, stirring and mixing water glass casting waste sand generated in an ester hardening process (sea sand water glass ester hardening process) with water according to the mass ratio of 1:1 to obtain an aqueous solution, and detecting that the pH value of the aqueous solution exceeds 14 by using a pH test paper;
s2, continuously stirring the aqueous solution at a stirring speed of 20rpm/min, adding ammonium chloride powder into the aqueous solution until the pH value of the aqueous solution is 13, and stopping adding the ammonium chloride powder;
s3, continuously adding calcium chloride dihydrate into the aqueous solution, wherein the aqueous solution quickly generates a white precipitate, continuously adding the calcium chloride dihydrate till the aqueous solution does not generate the white precipitate, stopping adding the calcium chloride and adding the flaky magnesium chloride hexahydrate, wherein the aqueous solution quickly generates the white precipitate, continuously adding the flaky magnesium chloride hexahydrate till the aqueous solution does not generate the white precipitate, stopping adding the flaky magnesium chloride hexahydrate, and continuously stirring for 40 min;
s4, continuously adding oxalic acid powder into the aqueous solution after 30min, wherein white precipitate is rapidly generated in the aqueous solution, continuously adding oxalic acid powder until the white precipitate is not generated in the aqueous solution, and stopping adding oxalic acid powder, wherein the pH value of the aqueous solution is 2-3;
s5, continuously adding hydrated lime into the aqueous solution, generating a large amount of bubbles in the aqueous solution, continuously adding soda ash until the pH value of the aqueous solution is 6-7, and stopping adding soda ash;
and S6, dehydrating the treated aqueous solution and drying at 100 ℃ to obtain the reclaimed sand.
Comparative example 1
The regeneration method of the water glass casting waste sand is different from the embodiment 2 in that: the step of adding oxalic acid is not included.
Comparative example 2
The regeneration method of the water glass casting waste sand is different from the embodiment 2 in that: the oxalic acid is replaced by acetic acid.
Example of detection
Physical properties of the casting molds made of the reclaimed sand prepared in examples 1 and 2 and the casting molds made of sea sand (new) prepared in comparative examples 1 and 2 were measured, and the measurement results are shown in table 1. Wherein Na2The method for measuring the content of O refers to the method for quickly measuring the content of O in P314-315, which is compiled by Van Hoda et al and is published in the technical theory and application technology of sodium silicate sand.
TABLE 1
It can be seen from table 1 that the sand mold prepared from the reclaimed sand prepared in example 2 is equivalent to the sand mold prepared from sea sand (newly), in initial compressive strength, final compressive strength and residual strength, and can completely reach the level of replacing sea sand. Examples 1 and 2 are all stronger than comparative examples 1 and 2 in initial compressive strength, final compressive strength and residual strength, i.e., it is shown that loosening the reclaimed sand by further adding oxalic acid in the reclamation method contributes to improving the bonding strength of the reclaimed sand with water glass. Both examples 1 and 2 are smaller in residual strength than comparative examples 1 and 2, i.e., it is shown that loosening of reclaimed sand by further adding oxalic acid in the reclaiming process contributes to improvement of the residual strength of reclaimed sand.
In summary, the invention provides a regeneration method of water glass casting waste sand, the regenerated sand prepared by the regeneration method, and a casting mold prepared by the regenerated sand, wherein ammonium chloride, calcium chloride and/or magnesium chloride are respectively added into an aqueous solution containing the water glass casting waste sand to reduce the modulus of high-modulus water glass in the water glass casting waste sand, so that the demolding rate and the recovery rate of the regenerated sand are effectively improved. Meanwhile, the pH value of the solution is controlled to avoid the generation of foul smell in the subsequent regeneration step and the use process of the regenerated sand due to the excessive addition of ammonium chloride. Furthermore, the oxalic acid is further added, so that the bonding strength (bonding strength/compressive strength) of the reclaimed sand prepared by the reclaiming method and the water glass can be further improved while the oxalic acid reacts with the residual magnesium chloride in the aqueous solution, and the obtained reclaimed sand is looser and has better fluidity compared with the existing reclaiming process, thereby further improving the performance of the reclaimed sand.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent modifications made by the present invention in the specification or directly or indirectly applied to the related technical field are included in the scope of the present invention.
Claims (8)
1. The regeneration method of the water glass casting waste sand is characterized by comprising the steps of respectively adding ammonium chloride, calcium chloride and/or magnesium chloride into an aqueous solution containing the water glass casting waste sand to reduce the high-modulus water glass modulus in the water glass casting waste sand;
and continuously adding oxalic acid until no white precipitate is generated in the aqueous solution, and dehydrating and drying to obtain the reclaimed sand.
2. The regeneration method of water glass casting waste sand according to claim 1, characterized by comprising the following steps:
s1, mixing the water glass casting waste sand with water according to the mass ratio of 1: 0.3-1.2 to obtain the aqueous solution;
s2, continuously stirring the aqueous solution, adding ammonium chloride into the aqueous solution until the pH value of the aqueous solution is 12-13, and stopping adding the ammonium chloride;
s3, continuously adding calcium chloride and/or magnesium chloride into the aqueous solution until no white precipitate is generated in the aqueous solution, stopping adding the calcium chloride and/or the magnesium chloride, and continuously stirring the aqueous solution;
and S4, continuously adding oxalic acid into the aqueous solution until no white precipitate is generated in the aqueous solution, stopping adding oxalic acid, and dehydrating and drying the aqueous solution to obtain reclaimed sand.
3. The regeneration method of water glass casting waste sand according to claim 2, further comprising, after the oxalic acid addition is stopped, S5, continuing to add soda ash or slaked lime into the aqueous solution until the pH of the aqueous solution is 6-7, stopping adding soda ash or slaked lime, and dehydrating and drying the aqueous solution to obtain regenerated sand.
4. The regeneration method of water glass foundry waste sand according to claim 2, wherein in S3, the stirring time for continuously stirring the aqueous solution is 30 to 40 min.
5. The regeneration method of water glass casting waste sand according to claim 2 or 3, characterized in that the drying condition is a drying temperature of 60-140 ℃.
6. The regeneration method of water glass foundry waste sand according to claim 1 or 2, characterized in that the water glass foundry waste sand is selected from waste sand produced in a carbon dioxide hardening process or in an ester hardening process.
7. A reclaimed sand produced by the method for reclaiming water glass foundry waste sand according to any one of claims 1 to 6.
8. A mold comprising water glass and reclaimed sand according to claim 7.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210100429.2A CN114406187A (en) | 2022-01-27 | 2022-01-27 | Regeneration method of waste water glass casting sand, regenerated sand and casting mold |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210100429.2A CN114406187A (en) | 2022-01-27 | 2022-01-27 | Regeneration method of waste water glass casting sand, regenerated sand and casting mold |
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| CN114406187A true CN114406187A (en) | 2022-04-29 |
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| CN202210100429.2A Pending CN114406187A (en) | 2022-01-27 | 2022-01-27 | Regeneration method of waste water glass casting sand, regenerated sand and casting mold |
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| CN111331071A (en) * | 2020-03-31 | 2020-06-26 | 福建蓝韵再生资源有限公司 | Method for preparing sodium silicate used sand through modification and regeneration |
| CN111515336A (en) * | 2020-04-21 | 2020-08-11 | 北京仁创砂业铸造材料有限公司 | Method for regenerating used sodium silicate sand |
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