Method and device for regenerating foundry sand

Abstract

A method for regenerating foundry sand, in particular for the renewed production of foundry molds and/or foundry mold cores from the regenerated foundry sand, through removal of binding agent, from a foundry sand/binding agent mixture, using a solid support means (6), wherein binding agent and support means (6) are separated from the foundry sand, wherein support means (6) is brought into contact with the foundry sand/binding agent mixture, is preferably added to it, and, together with the binding agent, which adheres thereto and/or which is incorporated therein, is separated from the foundry sand (10).

Claims

1. A method for regenerating foundry sand, for the renewed production of foundry molds and/or foundry mold cores from the regenerated foundry sand, through removal of binding agent, from a foundry sand/binding agent mixture, using a solid support means (6), wherein binding agent and support means (6) are separated from the foundry sand, wherein the support means (6) is brought into contact with the foundry sand/binding agent mixture as bulk material and is mixed therewith, wherein the solid support means is absorbent and/or adsorbent, wherein adhesion promotor (5) for improving the transport of the binding agent to the support means (6) and/or for improving the adhesion of the binding agent to and/or the incorporation of the binding agent in the support means (6) is added to the foundry sand/binding agent mixture, wherein the adhesion promoter (5) comprises or is a liquid, or is at least temporarily in liquid form by means of melting, with the simultaneous presence of the support means (6), and wherein the support means (6) together with the binding agent, which adheres thereto and/or which is incorporated therein, is separated from the foundry sand (10).

2. The method according to claim 1, wherein the bringing into contact of support means (6) and foundry sand/binding agent mixture takes place without previously washing out binding agent from the foundry sand/binding agent mixture with liquid.

3. The method according to claim 1, wherein adhesion promoter (5), maximally at a percentage by weight based on the weight of the foundry sand/binding agent mixture of less than 4% by weight, is added prior to and/or during the joint separation of binding agent and support means (6) from the foundry sand, and/or that a moisture content of the foundry sand/binding agent mixture, without considering the percentage by weight of the support means, during the entire regenerating method, has a % by weight value of less than 4% by weight and/or is set to such a % by weight.

4. The method according to claim 1, wherein the foundry sand/binding agent mixture is treated mechanically to remove binding agent from the foundry sand and/or to comminute binding agent.

5. The method according to claim 4, wherein the foundry sand/binding agent mixture is treated mechanically to remove the binding agent from the foundry sand and/or to comminute the binding agent prior to adding adhesion promoter (5) and/or support means, by moving relative to a pile of dust bodies.

6. The method according to claim 1, wherein binding agent removed from the foundry sand after a mechanical treatment and/or prior to an adhesion promoter addition, is separated by screening and/or air separation.

7. The method according to claim 1, wherein the bulk material is granular and/or powdery and/or fibrous.

8. The method according to claim 1, wherein the support means (6), together with the binding agent is separated continuously or in batches, under simultaneous at least partial drying of the support means, which is still mixed with the foundry sand/binding agent mixture, from the foundry sand from binding agent particles, by means of a heated gas stream.

9. The method according to claim 8, wherein the gas stream is heated to a temperature below 300° C. and/or the foundry sand, together with the binding agent, is maximally heated to a temperature below 220° C. during the separation of the support means.

10. The method according to claim 8, wherein the heated gas stream is an air stream in a moving bed.

11. The method according to claim 1, wherein the liquid is water.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages and details of the invention follow from the description below of a preferred exemplary embodiment by means of the sole FIG. 1, which shows a preferred exemplary embodiment of a method design or device, respectively, according to the invention.

DETAILED DESCRIPTION

(2) FIG. 1 shows a possible embodiment option of a regenerating method according to the invention. An unwashed foundry sand/binding agent mixture, which is to be treated, is added at 1. The present exemplary embodiment is an inorganic binding agent in the form of water glass with promoters. The supply is made into a mechanical treatment system 2, so as to remove binding agents from the foundry sand grains and/or to comminute them by means of the acting mechanical forces. The mechanical treatment preferably takes place in a dry manner, in the concrete exemplary embodiment by means of the “Clustreg” technology or treatment, respectively, described in DE 10 2013 001 801 B4, in the case of which the foundry sand/binding agent mixture is mechanically treated, in particular sheared, by means of a pile and a relatively movement.

(3) The result of the mechanical treatment, i.e. the mechanically treated foundry sand/binding agent mixture, which also contains fine-grained particles, in particular quartz sand particles and electrically charged particles, is transferred to a mixer 4 in 3. If necessary, the filling can be subjected to a screening or air separating step, in particular upstream of the mixer 4, for preferably cleaning the foundry sand/binding agent mixture in a dry manner from a binding agent portion and/or from fine-grained particles. In the specific exemplary embodiment, the addition of adhesion promotor 5, here for example in the form of water and of support means 6, here as an example in the form of wood fibers, takes place in any event in the mixer 4. In the concrete exemplary embodiment, the quantity of water is selected such that the moisture content of the foundry sand/binding agent mixture after a good mixing is 1.7% by weight here as an example, without considering the support means percentage by weight. In response to the mixing, an intensive contact of binding agent particles of the binding agent and support means takes place inside the mixer, whereby the binding agent particles adhere to the support means and/or are incorporated therein.

(4) The further transport of the mixture of foundry sand as well as support means with binding agent particles of the binding agent located therein to a splitter 8 (joint drying and separation) then takes place at 7, in that a drying of the foundry sand as well as at least partially of the support means takes place and the support means, together with the binding agent particle of the binding agent located therein, is discharged at 9, is thus separated from the foundry sand, which is discharged from the splitter in a dry manner at 10. The splitter 8 comprises a moving bed (fluidized bed), in which a gas stream 11, which is heated for example to 180° C. here, flows through foundry sand and support means with binding agent particles of the binding agent located thereon. It can be seen that the discharged support means is supplied to a separator 12, with the help of which support means with binding agent adhering thereto is separated from the discharge stream and is supplied to a combustion system 14 at 13. The exhaust gas is guided through a heat exchanger 15, which heats up a gas stream, here a fresh air stream 16, which then forms the gas stream 11 in the heated state. In addition or in the alternative, the pre-heated air stream 17, which was freed from the support means in the separator 12, is preferably used to heat the fresh air stream 16. In addition or as an alternative to the above-mentioned energy or heat sources, respectively, the external heat energy can be used at 18 to heat the fresh air stream 16, for example electrically, in a gaseous form, with liquid or solid energy sources.

(5) In addition or as an alternative to the heating of the fresh air stream, heat energy can be used (not shown), which is recovered from the regenerated sand, for example by means of a so-called sand temperature control or cooling device, respectively.

LIST OF REFERENCE NUMERALS

(6) 1 supply of foundry sand/binding agent mixture 2 mechanical treatment system 3 further transport 4 mixer 5 adhesion promoter 6 support means 7 forwarding 8 splitter for drying and separation 9 discharge (discharge stream comprising support means with binding agent arranged thereon) 10 discharge of cleaned (and optionally dried) foundry sand 11 gas stream 12 separator 13 supplying support means to the combustion system 14 combustion system 15 heat exchanger 16 fresh air stream 17 air stream 18 external heat energy