Method for producing a molding sand that is in particular recirculated, for foundry purposes
A method is for producing a moulding sand that is in particular recirculated, for foundry purposes. A mixture of a granular substance and aggregates, such as a binding agent and water, are added to a material that is not capable of swelling in water. The latter material has cavities with a specific surface area of more than 10 m 2 /g, in particular more than 50 m 2 /g and preferably more than 100 m 2 /g, for improving the characteristics of the moulding sand and/or for reducing the emission of harmful and/or odorous substances.
1. Method for producing a molding sand, for foundry purposes, comprising
adding a material that is not capable of swelling in water to a mixture of a granular substance and additives, and
a porous material that is not capable of swelling has cavities having a specific surface area of more than 10 m 2 /g, and
treating the porous material that is not capable of swelling chemically and/or physically in such a way that
oxidants are built into its cavities.
2. Method according to claim 1 ,
wherein cations and the oxidants are built into the cavities.
3. Method according to claim 1 ,
wherein a binder as well as water are used as additives.
4. Method according to claim 1 ,
wherein the porous material that is not capable of swelling has cavities having a specific surface area of more than 50 m 2 /g.
5. Method according to claim 1 ,
wherein the porous material that is not capable of swelling has a crystal structure and is equipped with pores for embedding harmful and/or odor-causing substances, without any significant change in the crystal structure.
6. Method according to claim 1 ,
wherein the material that is not capable of swelling has a low density of less than 3 g/cm 3 .
7. Method according to claim 1 ,
wherein the material that is not capable of swelling is a natural or synthetic material.
8. Method according to claim 1 ,
wherein hydrogen peroxide, oxalic acid, ozone, sodium percarbonate, are used as oxidants.
9. Method according to claim 1 ,
wherein structural silicates or tectosilicates, zeolite, but also pumice or pumice stone, allophane, imogolite, siliceous earth, polygarskites, sepiolites, diatomaceous earth, clays (treated with acid and/or heat), are used as porous materials that are not capable of swelling.
10. Method according to claim 1 , wherein the material that is not capable of swelling is added in amounts of approximately 0.1 wt.-% to approximately 40 wt.-%, with reference to an end product.
11. Method according to claim 1 , wherein the material that is not capable of swelling is added directly to the granular substance, the additives, or dispersed in water.
12. Method according to claim 1 ,
wherein a special zeolite, Fe zeolite or chabasite, is used as the porous material that is not capable of swelling.
13. Method according to claim 1 ,
wherein quartz sand, zirconium sand, chromite sand, olivine sand, or ceramic beads are used as the granular substance.
14. Method according to claim 1 ,
wherein a mixture is formed, which consists of 20 to 95 wt.-% of granular mass, 4 to 25 wt.-% of active binder clay, 1 to 12 wt.-% of water, 0.1 to 20 wt.-% of substances containing carbon, and 0.1 to 40 wt.-%, of structural silicates or tectosilicates.
15. Method according to claim 1 ,
wherein the porous material that is not capable of swelling has cavities having a specific surface area of more than 100 m 2 /g.
16. Method according to claim 1 ,
wherein the material that is not capable of swelling has a low density of less than 2.5 g/cm 3 .
17. Method according to claim 1 ,
wherein a mixture is formed, which consists of 20 to 95 wt.-% of granular mass, 4 to 25 wt.-% of active binder clay, 1 to 12 wt.-% of water, 0.1 to 20 wt.-% of substances containing carbon, and 0.1 to 20 wt.-%, of structural silicates or tectosilicates.