Hot dry method sodium silicate sand regeneration process and direct sand mixing molding method
By using the hot dry water glass sand regeneration process, high-temperature air heating and rubbing are used to remove impurities, solving the problem that regenerated sand cannot be 100% utilized in existing technologies. This enables direct mixing and molding of high-quality regenerated sand, reducing the probability of casting defects and production costs.
Patent Information
- Application Number
- CN202411427153.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-14
- Publication Date
- 2025-01-14
AI Technical Summary
Existing water glass sand recycling technology cannot achieve 100% recycling in the production of bolster side frame molding, resulting in high casting production costs.
The hot dry water glass sand regeneration process includes steps such as crushing, magnetic separation, thermal regeneration, dry regeneration and dust removal. Impurities and membranes are removed by heating with high-temperature air and rubbing, resulting in regenerated sand particles with smooth surfaces and high compactness.
It enables direct sand mixing molding with 100% recycled sand, reducing the probability of sand adhesion and sand hole defects in castings, and improving the recycling quality and recycling rate of old sand.
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of water glass sand regeneration and molding production, in particular to a hot dry water glass sand regeneration process and a molding process thereof, especially to the application in the production of bolster side frame castings. Background Art
[0002] Sand casting can be divided into clay sand casting, water glass sand casting and resin sand casting. The water glass sand casting process has many advantages, such as low cost, good fluidity, fast hardening, high dimensional accuracy, etc. However, there are also many problems in the application of the water glass sand casting process, such as poor disintegration, difficulty in sand falling, low recycling rate, etc. The random discarding of waste sand has caused very serious pollution to the environment. If the water glass sand can be reused, then the process will achieve clean and pollution-free production, so the regeneration of old sand has been considered to be an important problem that the water glass process should solve from the beginning.
[0003] When the regenerated water glass sand of the prior art is used in the production of bolster side frame molding, it is not possible to use 100% of the regenerated sand, and 30% to 40% of new sand needs to be added, resulting in a higher production cost of the casting. Summary of the invention
[0004] The technical problem to be solved by the present invention is: how to overcome the shortcomings of the existing water glass sand regeneration technology, provide a hot dry water glass sand regeneration process, and achieve 100% direct sand mixing and molding of the obtained water glass regenerated sand.
[0005] The technical solution adopted by the present invention is: a hot dry water glass sand regeneration process, which is carried out according to the following steps: Step 1: crushing, using a crusher to crush and screen the waste water glass sand recovered from casting to obtain waste water glass sand grains with a particle size ranging from the minimum particle size of the original water glass sand grains to twice the maximum particle size of the original water glass sand grains. During the screening process, the waste water glass sand grains larger than twice the maximum particle size of the original water glass sand grains are crushed and screened again; Step 2: Magnetic separation: Magnetic separation is performed on the screened wastewater glass sand particles to remove magnetic impurities; Step 3: thermal regeneration, preheating the wastewater glass sand grains after magnetic separation and then burning them to make the surface film of the wastewater glass sand grains brittle, cracked, and demolded, and then use a centrifuge to separate the demolded wastewater glass sand grains; Step 4, dry regeneration, placing the demoulding wastewater glass sand grains in a rubbing and rubbing regeneration machine for friction and rubbing, peeling off the residual film and inert film on the surface of the demoulding wastewater glass sand grains, and then using a centrifuge to separate the wastewater glass sand grains with clean surfaces; Step 5: Use a spiral cooling dust remover to remove dust from the waste water glass sand grains with clean surfaces, and screen out the waste water glass sand grains with clean surfaces whose dust removal particle size is from the minimum particle size of the original water glass sand grains to the maximum particle size of the original water glass sand grains; Step six, cooling the waste water glass sand particles to obtain regenerated water glass sand.
[0006] In step three, the waste water glass sand particles that have undergone magnetic separation are preheated and then calcined, the preheating temperature is 60-80°C, the calcination temperature is 200°C-260°C, and the calcination time is 30-60s.
[0007] In step three, during preheating, the cold sand falls from top to bottom, and the high-heat heating medium generated by gas combustion - air is used to heat the cold sand from bottom to top. The high-temperature hot air flow flows from bottom to top, removing free water, crystal water and some organic esters, making the water glass film on the surface of the sand grains brittle, greatly improving the regeneration quality of the old sand.
[0008] The invention discloses a sand mixing molding method for regenerated water glass sand prepared by a hot-drying water glass sand regeneration process. The method comprises the following steps: the regenerated water glass sand is uniformly mixed with water glass and organic ester by a continuous sand mixer; when mixing the sand, the regenerated water glass sand and organic ester are firstly added, and then the water glass is added; the modulus of the water glass is 1.95-2.3, the mass of the water glass is 2%-2.5% of the regenerated water glass sand, and the mass of the organic ester is 10%-13% of the water glass; the regenerated finished sand is uniformly mixed with the water glass and the organic ester and then dropped into a sand box for sand filling molding, and the sand mold is obtained by compacting, flattening, and flipping the mold.
[0009] The beneficial effects of the present invention are as follows: the present invention realizes 100% direct sand mixing and molding of recycled water glass sand without adding new sand, the obtained sand mold has a smooth surface, good compactness, high sand mold strength, and a low probability of defects such as sand sticking and sand holes in the casting.
[0010] The thermal regeneration method of the present invention utilizes the high heat generated by gas combustion to heat the medium - air, and then heats the sand through the high-temperature air. The heat exchange between the high-temperature hot air and the cold sand is carried out in a countercurrent manner, that is, the cold sand falls from top to bottom, and the high-temperature hot air flows from bottom to top, removing free water, crystal water and part of the organic ester, making the water glass film on the surface of the sand grains brittle, and greatly improving the regeneration quality of the old sand. The rubbing regeneration machine used in the dry regeneration of the present invention focuses on the rubbing and grinding of the sand grains, without the effects of striking and squeezing. The sand grains are not easy to break, and the membrane shell is easier to be removed. DETAILED DESCRIPTION
[0011] A hot-drying water glass sand regeneration process comprises the following steps: 1. Sand dropping: Use a vibrating sand dropping crusher to drop sand, crush and screen the castings after pouring; the main purpose of screening here is to remove the cold iron, core bone and other substances remaining in the old sand.
[0012] 2. Crushing magnetic separation: Use magnetic separation drum to separate ferromagnetic materials from old sand by magnetic force.
[0013] 3. Thermal regeneration: Using a roasting furnace, after the sand flows into the roasting furnace through the sand dividing cone, it first passes through the heat exchanger and undergoes countercurrent heat exchange with the rising high-temperature air to be fully preheated (about 60℃~80℃); when the hot sand falls through the combustion chamber, it comes into direct contact with the burning high-temperature flame for a short time and is burned by the high-temperature flame (200℃~260℃), causing the film on the surface of the sand particles to become brittle, cracked, and removed for regeneration.
[0014] 4. Dry regeneration: Use a rubbing regeneration machine. The water glass sand enters the rubbing regeneration machine from the feed port. Two sets of staggered friction disks rotate relative to each other at high speed. The sand particles are rubbed and rubbed during the high-temperature rotation. At the same time, the air flow blown by the high-pressure fan passes through the boiling plate to boil the sand particles. After the violent boiling collision and high-speed rubbing and friction, the residual film shell attached to the surface of the sand particles is removed.
[0015] 5. Dust removal: Use a vertical spiral cooling dust remover to remove dust from the regenerated sand.
[0016] 6. Cooling: Through water circulation, hot sand slowly flows from top to bottom, and the water in the countercurrent heat exchanger flows from bottom to top to ensure that the sand is fully cooled. Sand temperature ≤35℃.
[0017] Regenerated sand finished product inspection: (1) The residual sodium content in the water glass regenerated sand is detected by hydrochloric acid titration method, and the residual sodium is less than 0.3%; (2) The content of regenerated sand powder is less than 0.4%, and the moisture content is less than 0.3%; A sand mixing and molding method for regenerated water glass sand prepared by a hot dry water glass sand regeneration process comprises the following steps: uniformly mixing the regenerated finished sand, water glass and organic ester by a continuous sand mixer; firstly adding the organic ester to the water glass sand and then adding the water glass during the sand mixing; the water glass modulus is 1.95-2.3; the amount of water glass added is 2%-2.5% of the mass of the water glass sand; and the amount of organic ester added is 10%-13% of the mass of the water glass.
[0018] The regenerated finished sand is evenly mixed with water glass and organic ester and then dropped into a sand box for sand filling and molding. The sand mold is compacted, scraped flat, and turned over to obtain a sand mold.
[0019] 1. The thermal regeneration method of the present invention utilizes the high heat generated by gas combustion to heat the medium - air, and then heats the sand through the high-temperature air. The heat exchange between the high-temperature hot air and the cold sand is carried out in a countercurrent manner, that is, the cold sand falls from top to bottom, and the high-temperature hot air flows from bottom to top, removing free water, crystal water and part of organic esters, making the water glass film on the surface of the sand grains brittle, and greatly improving the regeneration quality of the old sand.
[0020] 2. The rubbing and grinding regeneration machine used in the dry regeneration of the present invention focuses on the rubbing and grinding effect of the sand particles, without the effect of hitting and squeezing. The sand particles are not easy to break, and the membrane shell is easier to be removed.
[0021] 3. The sand mixing molding process designed by the present invention can use 100% recycled sand during molding. The obtained sand mold has a smooth surface, good compactness, and high sand mold strength, which greatly reduces the probability of defects such as sand sticking and sand holes in castings.
Claims
1. A hot dry water glass sand regeneration process, characterized in that: Follow the steps below Step 1: crushing, using a crusher to crush and screen the waste water glass sand recovered from casting to obtain waste water glass sand grains with a particle size ranging from the minimum particle size of the original water glass sand grains to twice the maximum particle size of the original water glass sand grains. During the screening process, the waste water glass sand grains larger than twice the maximum particle size of the original water glass sand grains are crushed and screened again; Step 2: Magnetic separation: Magnetic separation is performed on the screened wastewater glass sand particles to remove magnetic impurities; Step 3: thermal regeneration, preheating the wastewater glass sand grains after magnetic separation and then burning them to make the surface film of the wastewater glass sand grains brittle, cracked, and demolded, and then use a centrifuge to separate the demolded wastewater glass sand grains; Step 4, dry regeneration, placing the demoulding wastewater glass sand grains in a rubbing and rubbing regeneration machine for friction and rubbing, peeling off the residual film and inert film on the surface of the demoulding wastewater glass sand grains, and then using a centrifuge to separate the wastewater glass sand grains with clean surfaces; Step 5: Use a spiral cooling dust remover to remove dust from the waste water glass sand grains with clean surfaces, and screen out the waste water glass sand grains with clean surfaces whose dust removal particle size is from the minimum particle size of the original water glass sand grains to the maximum particle size of the original water glass sand grains; Step six, cooling the waste water glass sand particles to obtain regenerated water glass sand.
2. A hot dry water glass sand regeneration process according to claim 1, characterized in that: In step three, the waste water glass sand particles that have undergone magnetic separation are preheated and then calcined, the preheating temperature is 60-80°C, the calcination temperature is 200°C-260°C, and the calcination time is 30-60s.
3. The hot-drying water glass sand regeneration process according to claim 1, characterized in that: In step three, during preheating, the cold sand falls from top to bottom, and the high-heat heating medium generated by gas combustion - air is used to heat the cold sand from bottom to top. The high-temperature hot air flow flows from bottom to top, removing free water, crystal water and some organic esters, making the water glass film on the surface of the sand grains brittle, greatly improving the regeneration quality of the old sand.
4. A sand mixing and molding method for regenerated water glass sand prepared by a hot dry water glass sand regeneration process according to claim 1, characterized in that: The regenerated water glass sand is mixed evenly with water glass and organic ester by a continuous sand mixer. When mixing the sand, the regenerated water glass sand and organic ester are added first, and then the water glass is added. The modulus of the water glass is 1.95-2.3, the mass of the water glass is 2%-2.5% of the regenerated water glass sand, and the mass of the organic ester is 10%-13% of the water glass. The regenerated finished sand is mixed evenly with the water glass and organic ester and then dropped into a sand box for sand filling and molding. The sand mold is obtained by compacting, scraping, and turning over the mold.