RU2356683C2 - Preparation method of sand blend - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to foundry. Method includes heating of fluidising agent, sputtering of lignosulphonate under high pressure on the surface of sand. Sputtering is implemented under high pressure in fluosolid layer of pulse action sprayer. Fluidising agent is heated up to the temperature 15…25 °C.

EFFECT: it is achieved increasing of mixture dry durability.

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Description

The invention relates to foundry, in particular to methods for preparing molding sand.

Known methods of coating in a fluidized bed, including a one-time loading of the required quantities of granular filler into a fluidized bed with its purge cooled to 0 ... 15 ° C with air containing a binder material with 100% humidity [RF Patent No. 2281831. A method of preparing molding sand. From 08/20/2006].

The disadvantage of this method for preparing the molding sand is the impossibility of applying thin films of lignosulfonate (LST) on the surface of sand grains due to the premature solidification of the finely divided substance LST in a cold fluidizing agent.

The objective of the invention is to obtain on the sand surface a stable thin film of LFB, which provides high strength of the mixture while reducing the consumption of binder and thereby improving the economic and environmental situation in the workplace.

This is achieved by the fact that the spraying is carried out in a fluidized bed with a temperature of 15 ... 25 ° C using nozzles of pulsed action under high pressure.

The essence of the proposed method is as follows: LFW using nozzles is sprayed quite finely by pulses in the gaps between which the LFW films are dried on the sand surface, which allows controlling the thickness of the binder films in the widest range without stopping sand boiling and air cooling.

Practical application of the method is shown in the following example. Mixtures were prepared in a fluidized bed: in the first case, at a temperature of 0 ... 15 ° C fluidizing agent and continuous spraying of lignosulfonate with air under a pressure of 6 at. As a result, mixtures with a dry strength of 0.12 ... 0.13 MPa were obtained. In another case, the temperature of the agent was increased to 15 ... 20 ° C and lignosulfonate was sprayed under a pressure of 150 atm with pulsating (pulse - 2 s, interruption - 5 s), ceteris paribus. The result was a dry strength of the mixture of 0.6 ... 0.8 MPa. Thus, on the face of the technical effect of the invention.

Literature

1. Patent of the Russian Federation No. 2281831. A method of preparing molding sand. From 08.20.2006.

Claims (1)

A method for preparing molding mixtures, comprising supplying a fluidizing agent and spraying lignosulfonate under pressure onto a sand surface in a fluidized bed by means of nozzles, characterized in that the spraying is carried out under high pressure by impulse nozzles, while the fluidizing agent is heated to a temperature of 15 ... 25 ° C.