CN109967693B - Additive for removing inert film of used casting sand and method for removing inert film of used casting sand - Google Patents
Additive for removing inert film of used casting sand and method for removing inert film of used casting sand Download PDFInfo
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- CN109967693B CN109967693B CN201910374349.4A CN201910374349A CN109967693B CN 109967693 B CN109967693 B CN 109967693B CN 201910374349 A CN201910374349 A CN 201910374349A CN 109967693 B CN109967693 B CN 109967693B
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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
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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
- B22C5/04—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
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Abstract
The application relates to the field of materials, in particular to an additive for removing an inert film of used casting sand and a method for removing the inert film of the used casting sand. The method for removing the inert film of the used foundry sand comprises the following steps: contacting the additive for removing the inert film of the used foundry sand with the inert film in a molten state; wherein, the additive for removing the inert film of the used foundry sand comprises one or more of calcium oxide, magnesium oxide and aluminum oxide; the used foundry sand is inorganic binder type used sand. The method provided by the embodiment of the application has great help to remove the inorganic salt inert film on the surface of the used foundry sand, and the demoulding rate of the inert film of the used foundry sand is increased; effectively improving the regeneration problem of the used foundry sand.
Description
Technical Field
The application relates to the field of materials, in particular to an additive for removing an inert film of used casting sand and a method for removing the inert film of the used casting sand.
Background
The inorganic binder (modified products of silicate and phosphate) is a material which is widely applied in casting, is different from other clay sand and resin molding materials, and has obvious advantages; but the defects are that the used sand is difficult to recycle, and the waste of the used sand easily causes environmental pollution and resource waste.
Disclosure of Invention
An object of the embodiments of the present application is to provide an additive for removing an inert film of used foundry sand and a method for removing an inert film of used foundry sand, which aim to solve the problem of difficult regeneration of used sand in the prior art.
The application provides in a first aspect a method for removing an inert film from used foundry sand, comprising:
contacting the additive for removing the inert film of the used foundry sand with the inert film in a molten state;
wherein, the additive for removing the inert film of the used foundry sand comprises one or more of calcium oxide, magnesium oxide and aluminum oxide; the used foundry sand is inorganic binder type used sand.
The additive for removing the inert film of the used foundry sand, which comprises one or more of calcium oxide, magnesium oxide and aluminum oxide, is contacted with the used foundry sand with the inert film in a molten state, and the additive for removing the inert film of the used foundry sand has at least one of the following two effects on the inert film:
first, the additive for removing the inert film of used foundry sand chemically reacts with the residual binder at high temperature to produce a high melting point powder or granular brittle material that is easily removed, for example, by mechanical grinding and negative pressure induced air.
For example, the following reaction occurs:
MgO+SiO2＝MgSiO3+CO2↑ CaO+SiO2＝CaSiO3+CO2↑
calcium oxide reacts with silicon dioxide to produce a brittle material, calcium silicate; magnesium oxide reacts with silicon dioxide to generate a brittle substance magnesium silicate; the melting point of the alumina is higher than 2054 ℃, and when the used sand residual binder is in a liquid state, the alumina is still granular.
The additive for removing the inert film of the used foundry sand comprises one or more of calcium oxide, magnesium oxide and aluminum oxide; after the reaction with the residual binder of the liquid used sand, one or two of calcium silicate and magnesium silicate are generated, or alumina which is not reacted and still is granular is generated.
The residual binder of the used sand is in a liquid state at high temperature, one or more of calcium silicate, magnesium silicate or aluminum oxide plays a role of nailing on the surface of the used sand grains, and the continuity of an inert film formed on the surface of the used sand grains is damaged, so that the inert film is not firmly wrapped outside the sand grains any more and is easy to remove.
Secondly, carbon dioxide gas is generated after the calcium oxide, the magnesium oxide and the liquid used sand residual binder act, and the gas can blow and crack the liquid inert film on the surface of the used sand to generate a crack effect; the decomposed substances of the additives removed from the casting used sand inert film are adsorbed on the inert film, so that the physical separation effect is realized, the growth of gel particles among sand grains is limited, and the solidification and agglomeration among the sand grains are effectively avoided.
The cracks destroy the continuity of the inert film formed on the surface of the old sand grains, so that the inert film is not firmly wrapped outside the sand grains any more and is easy to remove.
Any one of the two functions is beneficial to removing the inert film, and the demoulding rate of the casting used sand inert film is increased; the problem of difficult regeneration of used sand is improved.
In some embodiments of the first aspect of the present application, the additive to remove the inert film of foundry sand further comprises one or more of calcium carbonate, potassium carbonate, magnesium carbonate, and barium carbonate.
The blowing crack effect of the inert film can be improved by decomposing calcium carbonate, potassium carbonate, magnesium carbonate and barium carbonate to generate carbon dioxide; the function of physical partition is added to limit the growth of gel particles among sand grains, thereby effectively avoiding solidification and agglomeration among the sand grains.
In some embodiments of the first aspect of the present application, the additive to remove the inert film of foundry sand comprises alumina, magnesium carbonate, and magnesium oxide.
After the magnesium carbonate is decomposed, the carbon dioxide can blow and crack an inert film which is in a liquid state on the surface of the used sand to generate a crack effect; in addition, carbon dioxide, sodium silicate and magnesium oxide form magnesium silicate; the magnesium silicate plays a role of nailing on the surface of the used sand grains, and breaks the continuity of an inert film formed on the surface of the used sand grains. The two effects are simultaneously acted on the inert film; the demoulding rate of the casting used sand inert film is increased.
In some embodiments of the first aspect of the present application, the additive to remove the inert film of foundry sand comprises calcium oxide, calcium carbonate, and potassium carbonate.
The calcium carbonate and the potassium carbonate are decomposed to generate carbon dioxide gas, the gas can play a blowing and cracking role on the inert film on the surface of the used sand, and the calcium silicate and the potassium silicate can destroy the continuity of the inert film; the two effects simultaneously act on the inert film, and the demoulding rate of the casting used sand inert film is increased.
In some embodiments of the first aspect of the present application, the mixture mixed with the additive for removing the inert film of used foundry sand and used foundry sand is calcined at 500 ℃ to 800 ℃ for 2 to 8 hours.
The mixture and the additive for removing the inert film of the used foundry sand are roasted and heated together, so that the action time can be shortened, and the inert film can be quickly removed.
In some embodiments of the first aspect of the present disclosure, the mixture is fired and then ground prior to removing the inert film.
In some embodiments of the first aspect of the present application, the mixture is cooled to 100 ℃ to 400 ℃ after firing and then ground.
The particles on the surface of the roasted product increase the friction coefficient, so that the inert film and the particles are quickly crushed into powder, and the inert film is removed.
In some embodiments of the first aspect of the present application, in the mix: the mass of the additive for removing the inert film of the used foundry sand is 0.1 to 10 percent of the mass of the used foundry sand.
Under the proportion, the additive for removing the inert film of the used casting sand can be fully utilized; achieving higher demoulding rate.
In some embodiments of the first aspect of the present application, in the mix: the mass ratio of the inert film in the used foundry sand to the additive for removing the inert film in the used foundry sand is 1: 1-1.5.
Under the proportion, the additive for removing the inert film of the used casting sand can be fully utilized; achieving higher demoulding rate.
In a second aspect, the present application provides an additive for removing an inert film from foundry sand, the additive comprising a first material and a second material;
the first material comprises at least two components in parts by weight as follows: 1-3 parts of calcium oxide, 1-3 parts of magnesium oxide and 1-3 parts of aluminum oxide;
the second material comprises at least two components in parts by weight as follows: 2-4 parts of calcium carbonate, 2-4 parts of potassium carbonate, 2-4 parts of magnesium carbonate and 2-4 parts of barium carbonate;
optionally, the first material comprises at least two of the following components in parts by weight: 1.5-2.5 parts of calcium oxide, 1.3-2.2 parts of magnesium oxide and 1.5-2.6 parts of aluminum oxide; the second material comprises at least two components in parts by weight as follows: 2.5-3.3 parts of calcium carbonate, 2.3-3.6 parts of potassium carbonate, 2.6-3.2 parts of magnesium carbonate and 2.5-3.5 parts of barium carbonate;
optionally, the first material comprises the following components in parts by weight: 2 parts of calcium oxide, 2 parts of magnesium oxide, and 2 parts of aluminum oxide; the second material comprises the following components in parts by weight: 3 parts of calcium carbonate, 3 parts of potassium carbonate, 3 parts of magnesium carbonate and 3 parts of barium carbonate.
The calcium carbonate, the magnesium carbonate and the barium carbonate generate carbon dioxide gas at high temperature, and the carbon dioxide gas can play a role in blowing and cracking the liquid inert film on the surface of the used sand to generate a cracking effect; the calcium oxide and the magnesium oxide react with the silicon dioxide in the inert film to generate magnesium silicate and calcium silicate with higher melting points, and the aluminum oxide, the magnesium silicate and the calcium silicate with the higher melting points are adsorbed on the inert film and have the function of physical separation; and the 'nail-pricking' effect of the alumina, the magnesium silicate and the calcium silicate with high melting points is beneficial to removing the cooled inert film of the used casting sand, so that the removal rate of the inert film is increased, and the problem that the used casting sand is difficult to regenerate is solved.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The additive for removing the inert film of used foundry sand and the method for removing the inert film of used foundry sand according to the embodiments of the present application will be described in detail below.
The inorganic binder mainly contains silicate, phosphate or modified silicate or phosphate, and silica sand mainly contains silicon dioxide (SiO)2) And the mixture is heated to more than 150 ℃ to perform dehydration reaction to form silicic acid gel, so that sand grains are solidified and formed to form a film.
According to Na2O-Si2Binary phase diagram of O, β Na2O.2Si2O is in a liquid state at 678 ℃, and a flux is usually added to the inorganic binder for casting to modify the binder, so that the temperature at which O is in a liquid phase is also lowered.
The inorganic binder has serious caking at high temperature, poor collapsibility and difficult recycling of used sand; the waste sand is easy to cause environmental pollution and resource waste.
One reason for the difficulty in recycling used sand is that the inorganic binder, when used, forms an inert film on the surface of the sand grains, which firmly coats the sand grains and adheres to the surface of the sand grains mostly, except for a small portion that may be burned.
The inorganic old sand binder remained on the sand surface can not be burnt or directly decomposed after pouring, but forms a low-melting-point sodium silicate adhered on the silica sand surface, the sodium silicate presents a liquid phase in the high-temperature roasting stage, the temperature is reduced and then the sodium silicate is solidified and coated on the silica sand surface to present a firm vitreous body or crystal.
The residual binder in the used sand of the casting inorganic binder can be three parts:
about 10 percent of the refractory sand exists in a glass state, has high refractoriness, is adhered to the surface of sand grains, and cannot influence the integral use of recycled sand.
About 40 percent of the refractory sand exists in an inorganic salt state, and the inorganic salt state deteriorates the service life and the refractoriness of the recycled sand; the used sand needs to be removed when being regenerated.
About 50% of residual binder, namely reversibility and solubility, can be solidified due to loss of alkali and water loss, and can also be rehydrated to return to a liquid state to keep the binding activity, but can influence the service life; the used sand needs to be removed when being regenerated.
Generally, the regeneration treatment is carried out by the processes of crushing, heating, grinding and the like, the inert film is difficult to remove (the film removal rate is only 20% -30%), and alkaline inorganic salts such as sodium, potassium and the like are coated on the surface of the sand core, so that the conductivity of the reclaimed sand is high; the residual binder film on the sand has great influence on the recycling and regeneration of the used sand; the repeated use of the inorganic binder reclaimed sand can form a multi-layer shell, for example, the refractoriness and the bonding performance (hardening strength) of the sand are rapidly deteriorated, the reclaimed sand has high hygroscopicity and low refractoriness, and causes the defects of sand sticking and the like of castings, and the reclaimed sand cannot be directly used for replacing new sand core making and modeling. Therefore, the recycling of the used binder sand becomes a bottleneck limiting the large-scale use of the used binder sand.
The acidic substances (hydrochloric acid, sulfuric acid, oxalic acid and the like) are added into water to remove alkaline oxides on the surface of the silica sand, and the wet method is adopted to regenerate the old inorganic binder sand, so that the stripping effect is relatively good (the stripping rate can reach 80% -95%), the quality of the regenerated sand is high, but the wet regeneration cost of the old inorganic sand is very high and almost equal to that of new sand, and the treatment of alkaline sewage and precipitated sludge is difficult.
The application provides a method for removing an inert film of used foundry sand, which comprises the following steps:
contacting the additive for removing the inert film of the used foundry sand with the inert film in a molten state;
wherein, the additive for removing the inert film of the used foundry sand comprises one or more of calcium oxide, magnesium oxide and aluminum oxide; the used foundry sand is inorganic binder type used sand.
The inorganic binder type used sand refers to used sand produced by using an inorganic binder material (for example, silicate, phosphate, or modified silicate or phosphate) in casting production. In the embodiment of the present application, the inert film refers to a liquid film on the outer surface of the used sand at a high temperature, and the main components are sodium silicate, sodium oxide, silicon dioxide and the like.
The additive for removing the inert film of the used foundry sand, which comprises one or more of calcium oxide, magnesium oxide and aluminum oxide, is contacted with the used foundry sand with the inert film in a molten state, and the additive for removing the inert film of the used foundry sand has at least one of the following effects on the inert film:
first, the additive for removing the inert film of used foundry sand chemically reacts with the residual binder at high temperature to produce a high melting point powder or granular brittle material that is easily removed, for example, by mechanical grinding and negative pressure induced air.
For example, the following reaction occurs:
MgO+SiO2＝MgSiO3+CO2↑ CaO+SiO2＝CaSiO3+CO2↑
calcium oxide reacts with silicon dioxide to produce a brittle material, calcium silicate; magnesium oxide reacts with silicon dioxide to generate a brittle substance magnesium silicate; the melting point of the alumina is higher than 2054 ℃, and when the used sand residual binder is in a liquid state, the alumina is still granular.
The additive for removing the inert film of the used foundry sand comprises one or more of calcium oxide, magnesium oxide and aluminum oxide; after the reaction with the residual binder of the liquid used sand, one or two of calcium silicate and magnesium silicate are generated, or alumina which is not reacted and still is granular is generated.
The residual binder of the used sand is in a liquid state at high temperature, one or more of calcium silicate, magnesium silicate or aluminum oxide plays a role of nailing on the surface of the used sand grains, and the continuity of an inert film formed on the surface of the used sand grains is damaged, so that the inert film is not firmly wrapped outside the sand grains any more and is easy to remove.
Secondly, carbon dioxide gas is generated after the calcium oxide, the magnesium oxide and the liquid used sand residual binder act, and the gas can blow and crack the liquid inert film on the surface of the used sand to generate a crack effect; the decomposed substances of the additives removed from the casting used sand inert film are adsorbed on the inert film, so that the physical separation effect is realized, the growth of gel particles among sand grains is limited, and the solidification and agglomeration among the sand grains are effectively avoided.
The cracks destroy the continuity of the inert film formed on the surface of the old sand grains, so that the inert film is not firmly wrapped outside the sand grains any more and is easy to remove.
Any one of the two functions is beneficial to removing the inert film, and the demoulding rate of the casting used sand inert film is increased; the problem of difficult regeneration of used sand is improved.
In some embodiments of the first aspect of the present application, the additive to remove the inert film of foundry sand further comprises one or more of calcium carbonate, barium carbonate, potassium carbonate, and magnesium carbonate.
Calcium carbonate, potassium carbonate or magnesium carbonate generates carbon dioxide gas by thermal decomposition in a high temperature state, for example: CaCO3＝CaO+CO2↑；
MgCO3＝MgO+CO2↑；BaCO3+SiO2＝BaSiO3+CO2↑；
K2CO3+SiO2＝K2SiO3+CO2↑。
The carbon dioxide gas can increase the blowing cracking effect of the inert film; the function of physical partition is added to limit the growth of gel particles among sand grains, thereby effectively avoiding solidification and agglomeration among the sand grains.
In addition, in some embodiments, the following reaction is also performed:
MgO+CO2+NaO·mSiO2(liquid phase) ═ MgO · mSiO2(solid phase) + Na2CO3
The generation amount of the brittle magnesium silicate is increased so as to increase the nail pricking effect.
In some embodiments, the following reaction is also performed:
MgCO3+K2CO3＝MgK2(CO3)2forming a double salt
MgK2(CO3)2+2SiO2＝MgSiO3+K2SiO3+2CO2↑
Magnesium silicate and potassium silicate also have a "pinning" effect.
In some embodiments herein, the additive to remove the inert film of foundry sand includes alumina, magnesium carbonate, and magnesium oxide.
As mentioned above, MgCO3＝MgO+CO2↑；MgO+SiO2＝MgSiO3+CO2↑；
MgO+CO2+NaO·mSiO2(liquid phase) ═ MgO · mSiO2(solid phase) + Na2CO3；
The melting point of the alumina is higher than 2054 ℃, and when the used sand residual binder is in a liquid state, the alumina is still granular.
The gas can blow and crack the liquid inert film on the surface of the used sand to generate the effect of cracks; in addition, carbon dioxide and magnesium oxide form magnesium silicate; the magnesium silicate plays a role of nailing on the surface of the used sand grains, and breaks the continuity of an inert film formed on the surface of the used sand grains. The two effects are simultaneously acted on the inert film; the demoulding rate of the casting used sand inert film is increased.
By way of illustration, in some embodiments herein, the mass ratio of alumina, magnesium carbonate and magnesium oxide is 0.6-1.5: 0.6-1.5: 1; further, it may be 0.8 to 1.2: 0.8-1.2: 1; further, the ratio of 0.8: 1. in other embodiments of the present application, the alumina, magnesium carbonate, and magnesium oxide may be in any other proportions.
In some embodiments herein, the additives to remove the foundry-sand inert film include calcium oxide, calcium carbonate, and potassium carbonate.
CaCO3＝CaO+CO2↑；K2CO3+SiO2＝K2SiO3+CO2↑；
CaO+SiO2＝CaSiO3+CO2↑；
The gas can play a role in blowing and cracking the liquid inert film on the surface of the used sand to generate a cracking effect; calcium silicate and potassium silicate can disrupt the continuity of the inert film. The two effects are simultaneously acted on the inert film; the demoulding rate of the casting used sand inert film is increased.
As an illustration, in some embodiments herein, the mass ratio of calcium oxide, calcium carbonate, and potassium carbonate is 0.6 to 1.5: 0.6-1.5:0.6-1.5. Further, it may be 0.8 to 1.2: 0.8-1.2: 0.8-1.2; further, the ratio of 1: 1:1. in other embodiments of the present application, the mass ratio of calcium oxide, calcium carbonate, and potassium carbonate may be any other ratio.
Further, in some embodiments of the present application, the mixture mixed with the additive for removing the inert film of the used foundry sand and the used foundry sand is baked at 500-800 ℃ for 2-8 hours.
The mixture is roasted for 2 to 8 hours at the temperature of 500 ℃ and 800 ℃, and the inert film on the surface of the casting used sand is in a molten state; the additive for removing the inert film of the used foundry sand acts with the inert film.
The mixture and the additive for removing the inert film of the used foundry sand are roasted and heated together, so that the action time can be shortened, and the inert film can be quickly removed. In addition, since the low-melting substances on the surface of the foundry sand are small (the amount of ignition loss is low) after the high-temperature calcination, the refractoriness of the sand is improved, and the cast product after casting is less likely to be chemically bonded.
In other embodiments of the present application, the foundry used sand with the inert film in the molten state can also be obtained by other methods, such as calcination at a relatively high pressure and a relatively low temperature, it should be noted that the foundry used sand (except for the inert film) is not in the liquid state during calcination.
As an example, in a mix: the mass of the additive for removing the inert film of the used foundry sand is 0.1 to 10 percent of the mass of the used foundry sand. Further, the mass of the additive for removing the inert film of the used foundry sand is 2 to 8 percent of the mass of the used foundry sand, and further can be 5 to 7 percent.
As an example, in a mix: the mass ratio of the inert film in the used foundry sand to the additive for removing the inert film in the used foundry sand is 1: 1-1.8. Further may be 1: 1.3.
Under the proportion, the additive for removing the inert film of the used casting sand can be fully utilized; achieving higher demoulding rate.
Further, the mixture is ground after being calcined, and then the inert film is removed.
Grinding the mixture after roasting, increasing the friction coefficient of particles on the surface of a roasted product, quickly crushing the inert film and the particles into powder, and removing the inert film; for example, the broken inert film can be removed by negative pressure induced air; or removed by sieving.
Optionally, the mixture is cooled to 400 ℃ after being roasted, and then is ground. After the mixture is roasted, the mixture is cooled to 100-400 ℃, and in the grinding process, the additive for removing the inert film of the used casting sand further acts with the inert film while the collision and friction among the sand grains occur; in the grinding process, certain negative pressure is kept in the grinding equipment, and ground fine impurity powder is pumped away by dedusting and air inducing.
The method for removing the inert film of the used foundry sand provided by the embodiment of the application has high regeneration rate and high demoulding rate.
The casting used sand is subjected to the method for removing the inert film of the casting used sand to remove a large amount of inert films, so that the demolding rate is high; the yield is greater than ninety percent and the resulting foundry sand can be used in place of new sand.
The application also provides an additive for removing the inert film of the used foundry sand, which comprises a first material and a second material;
the first material comprises at least two components in parts by weight as follows: 1-3 parts of calcium oxide, 1-3 parts of magnesium oxide and 1-3 parts of aluminum oxide;
the second material comprises at least two components in parts by weight as follows: 2-4 parts of calcium carbonate, 2-4 parts of potassium carbonate, 2-4 parts of magnesium carbonate and 2-4 parts of barium carbonate.
Further, in some embodiments herein, the first material comprises at least two of the following components in parts by weight: 1.5-2.5 parts of calcium oxide, 1.3-2.2 parts of magnesium oxide and 1.5-2.6 parts of aluminum oxide. The second material comprises at least two components in parts by weight as follows: 2.5-3.3 parts of calcium carbonate, 2.3-3.6 parts of potassium carbonate, 2.6-3.2 parts of magnesium carbonate and 2.5-3.5 parts of barium carbonate;
further, in some embodiments herein, the first material comprises the following components in parts by weight: 2 parts of calcium oxide, 2 parts of magnesium oxide, and 2 parts of aluminum oxide; the second material comprises the following components in parts by weight: 3 parts of calcium carbonate, 3 parts of potassium carbonate, 3 parts of magnesium carbonate and 3 parts of barium carbonate.
The calcium carbonate, the magnesium carbonate and the barium carbonate generate carbon dioxide gas at high temperature, and the carbon dioxide gas can play a role in blowing and cracking the liquid inert film on the surface of the used sand to generate a cracking effect; the calcium oxide and the magnesium oxide react with the silicon dioxide in the inert film to generate magnesium silicate and calcium silicate with higher melting points, and the aluminum oxide, the magnesium silicate and the calcium silicate with the higher melting points are adsorbed on the inert film and have the function of physical separation; and the 'nail-pricking' effect of the alumina, the magnesium silicate and the calcium silicate with high melting points is beneficial to removing the cooled inert film of the used casting sand, so that the removal rate of the inert film is increased, and the problem that the used casting sand is difficult to regenerate is solved.
The features and properties of the present application are described in further detail below with reference to examples.
The foundry used sand samples of examples 1-13 and comparative example 1 were all the same and were all from used sand obtained after foundry of inner Mongolia raw sand.
Example 1
This example provides an additive for removing the inert film from foundry sand, and a foundry sand.
The additive for removing the inert film of the used foundry sand comprises the following components in a mass ratio of 2:1 of alumina, magnesium carbonate and magnesium oxide.
The foundry sand was prepared from foundry used sand and the additive for removing the inert film of foundry used sand provided in this example by the following method:
crushing the used foundry sand into particles; then mixing the mixture with the additive for removing the inert film of the used foundry sand provided by the embodiment to obtain a mixture; the mass of the additive for removing the inert film of the used foundry sand is 10 percent of the mass of the used foundry sand.
The mixture is put into a roasting furnace and roasted for 8 hours at 800 ℃.
And (3) feeding the roasted used foundry sand into a mechanical grinding machine at 400 ℃, performing collision and friction among sand grains, performing mechanical regeneration for 60min by a thermal method, keeping a certain negative pressure in grinding equipment, and pumping ground impurity fine powder away by dedusting and induced air. Reclaimed sand (foundry sand) was obtained by screening.
Example 2
This example provides an additive for removing the inert film from foundry sand, and a foundry sand.
The additive for removing the inert film of the used foundry sand comprises the following components in a mass ratio of 1: 2:2 calcium oxide, calcium carbonate and potassium carbonate.
The foundry sand was prepared from foundry used sand and the additive for removing the inert film of foundry used sand provided in this example by the following method:
mixing the used foundry sand with the additive for removing the inert film of the used foundry sand provided by the embodiment to obtain a mixture; the mass of the additive for removing the inert film of the used foundry sand is 10 percent of the mass of the used foundry sand.
The mixture is put into a roasting furnace and roasted for 8 hours at 800 ℃.
And (3) feeding the roasted used foundry sand into a mechanical grinding machine at 400 ℃, performing collision and friction among sand grains, performing mechanical regeneration for 60min by a thermal method, keeping a certain negative pressure in grinding equipment, and pumping ground impurity fine powder away by dedusting and induced air. Reclaimed sand (foundry sand) was obtained by screening.
Example 3
This example provides an additive for removing the inert film from foundry sand, and a foundry sand.
The additive for removing the inert film of the used foundry sand comprises the following components in a mass ratio of 2:3: 2:3:3 of alumina, magnesium oxide, magnesium carbonate, calcium oxide, calcium carbonate and potassium carbonate.
The foundry sand was prepared from foundry used sand and the additive for removing the inert film of foundry used sand provided in this example by the following method:
mixing the used foundry sand with the additive for removing the inert film of the used foundry sand provided by the embodiment to obtain a mixture; the mass of the additive for removing the inert film of the used foundry sand is 10 percent of the mass of the used foundry sand.
The mixture is put into a roasting furnace and roasted for 8 hours at 800 ℃.
And (3) feeding the roasted used foundry sand into a mechanical grinding machine at 400 ℃, performing collision and friction among sand grains, performing mechanical regeneration for 60min by a thermal method, keeping a certain negative pressure in grinding equipment, and pumping ground impurity fine powder away by dedusting and induced air. Reclaimed sand (foundry sand) was obtained by screening.
Example 4
This example provides an additive for removing the inert film from foundry sand, and a foundry sand.
The additive for removing the inert film of the used foundry sand is aluminum oxide.
The foundry sand was prepared from foundry used sand and the additive for removing the inert film of foundry used sand provided in this example by the following method:
crushing the used foundry sand into particles with the particle size of less than 10 mm; then mixing the mixture with the additive for removing the inert film of the used foundry sand provided by the embodiment to obtain a mixture; the mass of the additive for removing the inert film of the used foundry sand is 8 percent of the mass of the used foundry sand.
The mixture was put into a roasting furnace and roasted at 500 ℃ for 6 hours.
And (3) feeding the roasted used foundry sand into a mechanical grinding machine at 400 ℃, performing collision and friction among sand grains, performing mechanical regeneration for 60min by a thermal method, keeping a certain negative pressure in grinding equipment, and pumping ground impurity fine powder away by dedusting and induced air. Reclaimed sand (foundry sand) was obtained by screening.
Example 5
This example provides an additive for removing the inert film from foundry sand, and a foundry sand.
The additive for removing the casting used sand inert film is potassium carbonate.
The foundry sand was prepared from foundry used sand and the additive for removing the inert film of foundry used sand provided in this example by the following method:
crushing the used foundry sand into particles with the particle size of less than 10 mm; then mixing the mixture with the additive for removing the inert film of the used foundry sand provided by the embodiment to obtain a mixture; the mass of the additive for removing the inert film of the used foundry sand is 8 percent of the mass of the used foundry sand.
The mixture was put into a roasting furnace and roasted at 500 ℃ for 6 hours.
And (3) feeding the roasted used foundry sand into a mechanical grinding machine at 400 ℃, performing collision and friction among sand grains, performing mechanical regeneration for 60min by a thermal method, keeping a certain negative pressure in grinding equipment, and pumping ground impurity fine powder away by dedusting and induced air. Reclaimed sand (foundry sand) was obtained by screening.
Example 6
This example provides an additive for removing the inert film from foundry sand, and a foundry sand.
The additive for removing the casting used sand inert film is aluminum oxide and potassium carbonate with the mass ratio of 1:1.
The foundry sand was prepared from foundry used sand and the additive for removing the inert film of foundry used sand provided in this example by the following method:
crushing the used foundry sand into particles with the particle size of less than 10 mm; then mixing the mixture with the additive for removing the inert film of the used foundry sand provided by the embodiment to obtain a mixture; the mass of the additive for removing the inert film of the used foundry sand is 8 percent of the mass of the used foundry sand.
The mixture was put into a roasting furnace and roasted at 500 ℃ for 6 hours.
And (3) feeding the roasted used foundry sand into a mechanical grinding machine at 400 ℃, performing collision and friction among sand grains, performing mechanical regeneration for 60min by a thermal method, keeping a certain negative pressure in grinding equipment, and pumping ground impurity fine powder away by dedusting and induced air. Reclaimed sand (foundry sand) was obtained by screening.
Example 7
This example provides an additive for removing the inert film from foundry sand, and a foundry sand.
The additives for removing the inert film of the used foundry sand comprise calcium oxide, magnesium oxide, aluminum oxide, calcium carbonate, potassium carbonate, magnesium carbonate and barium carbonate in a mass ratio of 1.5:1.3:1.5:2.5:2.3:2.6: 2.5.
The foundry sand was prepared from foundry used sand and the additive for removing the inert film of foundry used sand provided in this example by the following method:
mixing the used foundry sand with the additive for removing the inert film of the used foundry sand provided by the embodiment to obtain a mixture; the mass of the additive for removing the inert film of the used foundry sand is 2 percent of the mass of the used foundry sand.
The mixture was put into a roasting furnace and roasted at 600 ℃ for 4 hours.
And (3) feeding the roasted used foundry sand into a mechanical grinding machine at 300 ℃, performing collision and friction among sand grains, performing mechanical regeneration for 25min by a thermal method, keeping a certain negative pressure in grinding equipment, and pumping ground impurity fine powder away by dedusting and induced air. Reclaimed sand (foundry sand) was obtained by screening.
Example 8
This example provides an additive for removing the inert film from foundry sand, and a foundry sand.
The additive for removing the inert film of the used foundry sand is magnesium oxide.
The foundry sand was prepared from foundry used sand and the additive for removing the inert film of foundry used sand provided in this example by the following method:
mixing the used foundry sand with the additive for removing the inert film of the used foundry sand provided by the embodiment to obtain a mixture; the mass of the additive for removing the inert film of the used foundry sand is 2 percent of the mass of the used foundry sand.
The mixture was put into a roasting furnace and roasted at 600 ℃ for 4 hours.
And (3) feeding the roasted used foundry sand into a mechanical grinding machine at 300 ℃, performing collision and friction among sand grains, performing mechanical regeneration for 25min by a thermal method, keeping a certain negative pressure in grinding equipment, and pumping ground impurity fine powder away by dedusting and induced air. Reclaimed sand (foundry sand) was obtained by screening.
Example 9
This example provides an additive for removing the inert film from foundry sand, and a foundry sand.
The additives for removing the casting used sand inert film are magnesium oxide and potassium carbonate in a ratio of 1:1.
The foundry sand was prepared from foundry used sand and the additive for removing the inert film of foundry used sand provided in this example by the following method:
mixing the used foundry sand with the additive for removing the inert film of the used foundry sand provided by the embodiment to obtain a mixture; the mass of the additive for removing the inert film of the used foundry sand is 2 percent of the mass of the used foundry sand.
The mixture was put into a roasting furnace and roasted at 600 ℃ for 4 hours.
And (3) feeding the roasted used foundry sand into a mechanical grinding machine at 300 ℃, performing collision and friction among sand grains, performing mechanical regeneration for 25min by a thermal method, keeping a certain negative pressure in grinding equipment, and pumping ground impurity fine powder away by dedusting and induced air. Reclaimed sand (foundry sand) was obtained by screening.
Example 10
The embodiment provides an additive for removing an inert film of used foundry sand, which comprises the following components in parts by weight:
1 part of calcium oxide, 1 part of magnesium oxide, 2 parts of calcium carbonate, 2 parts of potassium carbonate and 4 parts of magnesium carbonate.
The foundry sand is obtained by reacting the additive for removing the inert film of the foundry sand provided by the embodiment with the foundry sand, and the specific regeneration method is the same as that of the embodiment 1.
Example 11
The embodiment provides an additive for removing an inert film of used foundry sand, which comprises the following components in parts by weight:
2.5 parts of calcium oxide, 1.3 parts of magnesium oxide, 1.5 parts of aluminum oxide, 2.5 parts of calcium carbonate, 3.6 parts of potassium carbonate, 3.2 parts of magnesium carbonate and 2.8 parts of barium carbonate.
The foundry sand is obtained by reacting the additive for removing the inert film of the foundry sand provided by the embodiment with the foundry sand, and the specific regeneration method is the same as that of the embodiment 1.
Example 12
The embodiment provides an additive for removing an inert film of used foundry sand, which comprises the following components in parts by weight:
2.5 parts of calcium oxide, 2.6 parts of aluminum oxide, 3.3 parts of calcium carbonate, 2.3 parts of potassium carbonate and 2.6 parts of magnesium carbonate.
The foundry sand is obtained by reacting the additive for removing the inert film of the foundry sand provided by the embodiment with the foundry sand, and the specific regeneration method is the same as that of the embodiment 1.
Example 13
The embodiment provides an additive for removing an inert film of used foundry sand, which comprises the following components in parts by weight:
2 parts of calcium oxide, 2 parts of magnesium oxide, and 2 parts of aluminum oxide; the second material comprises the following components in parts by weight: 3 parts of calcium carbonate, 3 parts of potassium carbonate, 3 parts of magnesium carbonate and 3 parts of barium carbonate.
The foundry sand is obtained by reacting the additive for removing the inert film of the foundry sand provided by the embodiment with the foundry sand, and the specific regeneration method is the same as that of the embodiment 1.
Comparative example 1
The present comparative example provides a foundry sand prepared by essentially the steps of:
the used foundry sand is put into a roasting furnace and roasted for 4 hours at 600 ℃.
And (3) feeding the roasted used foundry sand into a mechanical grinding machine at 300 ℃, performing collision and friction among sand grains, performing mechanical regeneration for 25min by a thermal method, keeping a certain negative pressure in grinding equipment, pumping ground impurity fine powder out by dedusting and induced air, and screening.
Test example 1
The performance of the inner covering raw sand, the used foundry sand and the foundry sand provided in examples 1 to 13 was measured, and the results are summarized in table 1.
TABLE 1 Performance data for raw foundry sand, used foundry sand and foundry sand of the examples
| Detecting items | Used foundry sand | Foundry sand of each example | Inner covering raw sand |
| Acid consumption value ml | 30-45 | 5.0-6.0 | 5.0 |
| Na2Percentage of O | 1.0-2.0 | ≤0.05 | ≤0.02 |
| Conductivity μ s/cm | ≥2400 | ≤230 | ≤100 |
| Reduction on ignition% | 1.2-2.0 | ≤0.15 | ≤0.3 |
| Water content% | 0.2-05 | ≤0.10 | ≤0.2 |
| Tensile strength MPa | - | 1.80 | 0.80 |
Conductivity (Conductivity) is a parameter for describing the difficulty of charge flow in a substance, and the amount of soluble inorganic salt on the surface of silica sand can be directly reflected in the invention, and the higher the Conductivity, the more the amount of inorganic salt on the surface of silica sand.
As can be seen from Table 1, Na is present in examples 1 to 92The removal rate of O reaches more than 90 percent, the physical and chemical properties of the casting sand of each embodiment are close to those of the original sand, and after high-temperature roasting, the low-melting-point substances on the surface of the casting sand of each embodiment are few (the ignition loss is low), so the refractoriness of the sand is improved, and the cast is not easy to generate chemical bonding; next, the water content of the foundry sand of each example was also very low, and the core of the inorganic binder was generally a process of dehydration by heating and curing, so that each example was madeThe solidification efficiency is improved when the casting sand is used for core making, and the use performance is superior to that of the original sand comprehensively.
Test example 2
The foundry sand provided in examples 4 to 6 and the used foundry sand were subjected to tests and calculation of costs.
The effect of different adjuvants on the removal rate of inorganic binder films was compared under the same regeneration process.
Table 2 properties of foundry sands and foundry used sands provided in examples 4-6
| Serial number | Example 4 | Example 5 | Example 6 | Used foundry sand |
| Conductivity us/cm | 223 | 382 | 253 | 1983 |
| Cost increase yuan/ton | 50-60 | 15-20 | 25-35 | 0 |
As can be seen from Table 2, the regeneration effect in example 4 is better, and the content of inorganic salts on the appearance of the foundry sand is low; the effect of alumina alone as an additive was shown to be superior to the mixture of potassium carbonate and alumina; further superior to potassium carbonate alone. But the cost increase of the alumina alone as an additive is higher.
Test example 3
The foundry sand provided in example 8 and the foundry sand provided in comparative example 1 were examined for electrical conductivity; the results are given as: the conductivity of the foundry sand provided in example 8 was 208 us/cm; the foundry sand provided in comparative example 1 had an electrical conductivity of 1886 us/cm.
The conductivity of the used foundry sand in reference test example 2 was 1983 us/cm.
It can be seen that: the conductivity of the foundry sand provided in example 8 was reduced by 91.1% compared to that of the foundry used sand, and the conductivity of the foundry sand provided in comparative example 1 was reduced by only 19.7%.
The conductivity of the reclaimed sand after the auxiliary agent is reduced by 91.1 percent, and the conductivity of the control group without the auxiliary agent is reduced by only 19.7 percent, which shows that the inorganic salt of the additive for removing the inert film of the used foundry sand provided by the example 8 has good removal effect.
Test example 4
The foundry sand provided by the example 9 is used for a plurality of times, and after the foundry used sand is obtained, the additive for removing the inert film of the foundry used sand (the additive for removing the inert film of the foundry used sand provided by the example 9) is used for regeneration, and then the foundry sand is used; circulating; the process is roughly as follows: reclaimed sand → core making, casting → regeneration treatment → reclaimed sand → core making, casting → circulation for 5 times. The used foundry sand was used as a control without any additives. The results are shown in Table 3.
Table 3 conductivity (us/cm) of foundry sand provided in example 9 before recycle
| Group of | Example 9 provides additives | Control group |
| Circulating for 1 time | 271 | 1792 |
| Circulating for 2 times | 255 | 2013 |
| Circulating for 3 times | 250 | 2345 |
| Circulating for 4 times | 236 | 2461 |
| Circulating for 5 times | 220 | 2798 |
As can be seen from table 3: the used foundry sand is regenerated by the additive for removing the inert film of the used foundry sand provided in the embodiment 9, the used foundry sand with higher conductivity is recycled for 5 times, and the conductivity does not rise; the conductivity of the control group is continuously increased, which shows that if the residual inorganic salt does not remove the binder coated on the sand grains during the circulation use of the sand, the secondary mixing use inevitably causes the accumulation of excessive inorganic salt.
In conclusion, the additive for removing the inert film of the used foundry sand provided by the embodiment of the application is very helpful for inorganic salts on the surface of the used foundry sand, and effectively improves the regeneration problem of the used foundry sand.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (9)
1. A method of removing an inert film from foundry sand, comprising:
contacting the additive for removing the inert film of the used foundry sand with the inert film in a molten state;
wherein the foundry used sand is inorganic binder type used sand; the additive for removing the foundry used sand inert film comprises a first material and a second material;
the first material comprises at least two components in parts by weight as follows: 1-3 parts of calcium oxide, 1-3 parts of magnesium oxide and 1-3 parts of aluminum oxide;
the second material comprises at least two components in parts by weight as follows: 2-4 parts of calcium carbonate, 2-4 parts of potassium carbonate, 2-4 parts of magnesium carbonate and 2-4 parts of barium carbonate.
2. The method for removing the inert film of the foundry used sand according to claim 1, wherein the mixture of the additive for removing the inert film of the foundry used sand and the foundry used sand is baked at 500 ℃ to 800 ℃ for 2 to 8 hours.
3. The method for removing the inert film from the used foundry sand as recited in claim 2, wherein the mixture is calcined, ground and then the inert film is removed.
4. The method for removing the inert film from the foundry used sand according to claim 3, wherein the mixture is cooled to 100-400 ℃ after being roasted and then ground.
5. The method for removing inert film of foundry sand according to claim 2,
in the mixture: the mass of the additive for removing the inert film of the used foundry sand is 0.1-10% of the mass of the used foundry sand.
6. The method for removing inert film of foundry sand according to claim 2,
in the mixture: the mass ratio of the inert film in the used foundry sand to the additive for removing the inert film in the used foundry sand is 1: 1-1.5.
7. An additive suitable for use in the method of removing an inert film of foundry sand of claim 1, wherein the additive comprises a first material and a second material;
the first material comprises at least two components in parts by weight as follows: 1-3 parts of calcium oxide, 1-3 parts of magnesium oxide and 1-3 parts of aluminum oxide;
the second material comprises at least two components in parts by weight as follows: 2-4 parts of calcium carbonate, 2-4 parts of potassium carbonate, 2-4 parts of magnesium carbonate and 2-4 parts of barium carbonate.
8. Additive according to claim 7, wherein the first material comprises at least two of the following components in parts by weight: 1.5-2.5 parts of said calcium oxide, 1.3-2.2 parts of said magnesium oxide, and 1.5-2.6 parts of said aluminum oxide; the second material comprises at least two components in parts by weight as follows: 2.5-3.3 parts of calcium carbonate, 2.3-3.6 parts of potassium carbonate, 2.6-3.2 parts of magnesium carbonate and 2.5-3.5 parts of barium carbonate.
9. Additive according to claim 7, wherein the first material comprises the following components in parts by weight: 2 parts of said calcium oxide, 2 parts of said magnesium oxide, and 2 parts of said aluminum oxide; the second material comprises the following components in parts by weight: 3 parts of the calcium carbonate, 3 parts of the potassium carbonate, 3 parts of the magnesium carbonate and 3 parts of the barium carbonate.
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| CN110434280B (en) * | 2019-09-03 | 2021-01-26 | 南阳仁创砂业科技有限公司 | Regeneration method of inorganic used sand of water glass |
| CN110405136B (en) * | 2019-09-04 | 2021-02-19 | 北京仁创砂业铸造材料有限公司 | Wet regeneration additive and regeneration method for silicate foundry used sand |
| CN110523917B (en) * | 2019-09-09 | 2020-09-22 | 武汉纺织大学 | Novel chemical regeneration method for used sodium silicate sand |
| CN110640080A (en) * | 2019-09-09 | 2020-01-03 | 武汉纺织大学 | Waste water glass sand wet regeneration method without wastewater discharge |
| CN110615687B (en) * | 2019-11-01 | 2022-05-13 | 内蒙古仁创沙产业有限公司 | Purification method of casting silica sand and high-purity silica sand |
| CN112605336B (en) * | 2020-11-30 | 2022-09-20 | 襄阳仁创铸造材料有限公司 | Preparation method and application of reclaimed sand for casting cold core |
| CN114130947A (en) * | 2021-11-26 | 2022-03-04 | 通辽市仁创铸造材料有限公司 | Regeneration method of inorganic reclaimed sand |
| CN117483640B (en) * | 2023-11-17 | 2024-04-19 | 郑州煤机格林材料科技有限公司 | Regeneration treatment process for used sand in sodium silicate sand mold casting |
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| JP2001205388A (en) * | 2000-01-20 | 2001-07-31 | Gun Ei Chem Ind Co Ltd | Method for thermal regeneration of molding sand and method for manufacturing casting mold for casting |
| CN1323779C (en) * | 2002-09-13 | 2007-07-04 | 李明星 | Renovation and reclamation process for silicate-bonded sand |
| GB0410484D0 (en) * | 2004-05-11 | 2004-06-16 | Ashland Uk Ltd | Reclamation of ester-cured phenolic resin bonded foundry sands |
| DE102007008149A1 (en) * | 2007-02-19 | 2008-08-21 | Ashland-Südchemie-Kernfest GmbH | Thermal regeneration of foundry sand |
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| CN107008851B (en) * | 2017-04-10 | 2019-10-18 | 合肥仁创铸造材料有限公司 | A kind of inorganic sand and organic sand mixed regeneration method and its reclaimed sand |
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