SU1720780A1 - Method of regeneration of molding and core sand - Google Patents

Abstract

The invention relates to foundry and is intended to improve the quality of the regeneration of molding sands by more completely removing dust-like fractions from their surface. The purpose of the invention is to improve the quality of regeneration. The mixture is dried, subjected to magnetic separation, crushing and sieving. Then it is supplied together with compressed air into the dispersion pipe 4, while the content of the mixture in the airflow is 0.2-2.0%. On the path of the flow perpendicular to the axis of the expansion pipe, rod-barrier 5 is placed at a distance I from the entrance to the pipe 4, / 4 f determined from the expression: I K --- where d is the diameter of the rod, cm; C is the speed of sound in air, cm / s; V - mixture flow rate, cm / s; K is an empirical coefficient equal to 0.4-0.6. The ratio of the total length L, the diameter d of the expansion pipe and the distance I of the rod – obstacles from the entrance to the pipe is established in accordance with the expression L: d: 1 10: (1-2): 2.5. The dust-like particles separated from the surface of the granules are removed by an exhaust ventilation system 7. 1 Il, 3 tab. (L

Description

The invention relates to foundry, in particular to methods for the regeneration of molding and core sands,

The known method of regeneration of sand 1. The method includes the supply of the regenerated mixture into the mixing chamber, compressed air and waste mix into the accelerating pipe and the collision of sand particles with a reflector cap. To increase the kinetic energy of the impact, sand particles are reported to move from top to bottom. During the impact on the cap, which is located convexly upwards, the surface of the quartz sand is cleaned from the binder residue.

Of the known methods of regeneration of molding and core mixtures, the closest in technical essence to the proposed method is the method of regeneration of molding sand (British Patent 1322864, class B 22 C 5/18, 1973). The known method consists in performing successive operations — in magnetization separation, crushing, cooling, and special processing in a unit in which vertically incoming sand is blown by horizontal air jets directing the sand to reflective shields at an angle to the flow of sand. Then the sand goes to the next processing stage, where the process is repeated again. To improve cooling from

a special sprayer in the upper part of the unit is introduced a thin stream of water,

The disadvantage of this method is that it is impossible to remove residual binder shells from the recesses and irregularities of sand particles in the process of mutual friction and movement along the surfaces of the reflective plates. In addition, sand moistening with water jets occurs unevenly, which leads to the clumping of both regenerate and quartz sand, which makes it difficult to properly clean the surface of sand particles.

The purpose of the present invention is to improve the quality of regeneration due to a more complete removal from the surface of the granules of a mixture of unwanted aggregates of dust-like fractions.

The goal is achieved by the fact that in the method of regeneration of the molding mixture, including drying, magnetic separation, crushing, sifting the mixture, feeding compressed air through the accelerating tube and suction of dusty air, the mixture is fed into the accelerating tube at 0.2-2 , 0%. Another difference of the proposed method lies in the fact that perpendicular to the flow of granules and the axis of the accelerating tube establish a rod-barrier at a distance I from its course, determined from the expression:

D With

1 KV

0)

where is the distance from the entrance to the accelerating tube to the rod – obstacles, cm;

D is the diameter of the rod, cm;

C is the speed of sound in air, cm / s;

V - mixture flow rate, cm / s;

K - energy coefficient equal to 0.4-0.6.

The drawing shows a device for implementing the method.

The device comprises a blower fan 1, an injection pipe 2, a hopper 3, a run-up pipe 4 in which a bar 5 is installed perpendicular to the flow of granules 6 at a distance I from the entrance to the pipe 4, determined from expression (1). The ratio of the total length L, the diameter d of the expansion tube and the distance I is set equal to 10: (1-2): 2.5. The device also contains a ventilation system 7. The previously prepared granular material after drying, crushing, sieving through a sieve with the aim of elimination of the granules with a size that is technologically acceptable and magnetic separation is fed into the device. After turning on the fan 1

and supplying compressed air to the injection pipe 2 through the gap between the pipe 2 and the loading hopper 3, the flow of pellets 6 is supplied to the accelerating pipe 4, the flow around the rod-obstacle 5, at a volume content of 0.2-2.0% in the air flow. The flow of the granules 6 oscillates in the vortices, alternately breaking from the rod of the barrier 5. In the process of several hundred oscillations, the surface of the granules is cleared of undesirable impurities. The dust particles from the surface of the granules are removed by an exhaust ventilation system 7,

Example. The proposed method was tested on a pilot plant (accelerating tube 32 cm long, 4.6 cm diameter, rod-barrier 1 cm in diameter). Extending the ventilation system created a discharge of 10 mm. waters Art. Flow rate

the pellets were 2000 cm / s, the rod in the expansion pipe was set at a distance of 8 cm from the entrance. The setting allowed the main parameters to be changed in the following ranges; pipe length L

20-100 cm; the diameter d of the expansion pipe 2 - 10 cm; the distance I from the entrance to the expansion pipe to the rod – barrier I is 2.0–30 cm. The flow velocity of the granules could be 10, 20, 30 m / s; The concentration of granules in the stream varied from 0.1 to 3.0 vol.%. Experimental studies were carried out on dump sand-clay mixtures that underwent preliminary operations: drying at 100-150 ° C (1 h); jaw crushing

the grinder, followed by sieving through a sieve of 3 to 3 mm, magnetic separation to remove metallic inclusions (the original clay was 12.64%). The consumption of granulated material

controlled by the size of the gap between the walls of the loading hopper and the injection pipe. The quality of the regenerate obtained was characterized by a change in the clay component (GOST 2340918-78)

and the sum of fine fractions (fractions 0063, 005 and-005 according to GOST 23409,24-78), gas permeability (GOST 234096-78).

The effect of the volume concentration of granular material on the quality of the regenerate is shown in Table. 1. As can be seen from the table, the minimum content of harmful impurities (clay component and fine fractions) was obtained with a volume concentration in the range of

0.2-2%.

In tab. Figure 2 shows the relationship between the flow rate of the granulated material and the distance from the entrance to the accelerating tube to the installation site of the bar-barrier at different values of the empirical coefficient. The optimal value of 0.4-0.6.

The large influence on the output of a quality regenerate has a diameter of the expansion pipe. As can be seen from the table. 3, the optimum value of the diameter of the expansion pipe is (0.4-0.8) I.

Claims (1)

The invention of the method of regeneration of the molding and core mixture, including drying, magnetic separation, crushing and sieving of the mixture, feeding compressed air through the accelerating tube and suction of dusty air, so that, in order to improve the quality of regeneration a mixture in an accelerating pipe is supplied with its volume content in the air flow of 0.2-2.0%, using a bar-barrier installed perpendicular to the flow of granules and the axis of the accelerating pipe at a distance (I) from its entrance, determined from the mathematical expression : dC I k V (cm) where d is the diameter of the rod, cm; C is the speed of sound in air, cm / s; V - mixture flow rate, cm / s; K-empirical coefficient equal to 0.4-0.6. 15 ate with 1 8 cm; L 32 cm; 8.76 5.84 300 7.46 5.60 320 7.52 5.60 310 7.48 5.50 312 , 6cM; D 1cM; V 2000 cm / s 1 16 cm; L 64 cm; 8.60 5.60 320 7.40 5.70 318 7.40 5.6k 310., 7.38 5.60 316 .. d 6.0 cm; D 1 cm V 1000 cm / s 1 6.0 cm; L 24 cm; 8.50 5.40 310 7.20 5.30 320 7.28 5.38 300 7.30 5.40 312 d 2.5 cm; D 1 cm; V 3000 cm / s 8.94 6.04 2.98 8, 5, W ge 5.64,290 -J short oh so 8 CM; L 2,0 CM 8 CM; L 3,2 CM 8 cM; L 4,6 CM 8 CM; L 6.4 CM 8 CM; L 8.0 CM 32 CM; 32 CM; 32 CM; 32 CM; 32 CM; 7.56 5.96 5.80 5.70 8.16 196,274,264,368 172