SU1468646A1 - Method of producing heat-insulating mixture for casting steel - Google Patents

Abstract

The invention relates to the field of metallurgy, in particular to methods for producing heat insulating mixtures used in casting steel into molds. The purpose of the invention is to reduce the shrinkage defects in the head of an ingot by improving the thermal insulating properties of the mixture - achieved by implementing a method that includes drying pre-mixed lignin and perlite sand rock at 105-400 ° C and an air excess factor (X 0.1-0.3 , and firing this mixture at 760–960 ° C and an excess air ratio of 0.2–0.8. Due to the swelling of perlite sand during firing, the formed perlite particles are covered with pyrolysis carbon, and the resulting heat insulating material It has a low net weight (80-100 kg / m), has a higher insulating capacity, which ensures, when using the mixture, the enhanced effect of insulating the head portion of the ingot, which reduces the length of shrinkable defects. Table 2 . (/)

Description

one

The invention relates to metallurgy, in particular to methods for producing heat insulating mixtures used in casting steel into molds.

The aim of the invention is to reduce (the extent of shrinkage defects in the head part of the ingot is due to the improvement of the heat insulating properties of the mixture.

Ta.bl.1 shows examples of the implementation of the method according to the invention. At this, for the preparation of a heat insulating mixture, the rock of perlite sand from the Aragats deposit and the lignin of the Zaporizhia hydrolysis plant were used in a 1: 1 ratio.

 Table 2 presents data on the properties and results of the application of the proposed heat insulating mixture. The length of shrinkage defects was determined by the UT method in an ingot billet weighing 7.4 tons.

The production of perlite-carbon thermal insulation mixture by the proposed method is carried out in two stages. At the first stage, the wet lignin is dried, excess water is removed from the rock of perlite sand, and the raw materials are pelletized into granules of 0.5-5.0 mm in size. The temperature in the first stage of processing the mixture increases from

bi oo

O5 4

O5

105 to AOO C. At the same time, along with the removal of excess moisture, low-temperature volatiles are released from lignin, and pelletized particles are covered with pyrolysis carbon. Pyrolysis gases are burned in the drying zone, compensating for the costs of removing excess moisture and heating the material.

In the second stage of the process of obtaining a heat insulating mixture, the amount of air supplied for the combustion of pyrolytic gases increases significantly, which leads to an increase in the temperature of the flue gases to 760–960 s. Particles of perlite sand with lignin in the gas stream undergo thermal shock. The result is a swelling of perlite. With a lack of air for complete combustion of pyrolysis gases and black carbon of lignin, the formed perlite particles are covered with a layer of pyrolysis carbon, have a low bulk density and high heat insulating ability (see Table 2). Due to the indicated properties of the proposed mixture, the shrinkage defects and the head section of the ingot are reduced.

Formula inventions

burning the mixture is additionally dried at 105-400 ° C and an air excess factor of 0.1-0.3.

Table 1

The method of obtaining heat insulating

steel casting mixtures including pre-mixed ligni roasting

on and mineral filler in the ratio of 1: 0.2-2.0 at 760-960 C and air excess factor of 0.2-0.8, Q distinguishing, so that

In order to reduce the length of the daughter defects in the head section, due to the improvement of the thermal insulating properties of the mixture, a rock of perlite sand is used as a mineral filler, and before

90

80

100

Heat supply coefficient C, w / m

0.11 0.09 0.13

14.5 12.5 14.5

Claims (1)

Claim A method of obtaining a heat-insulating mixture for casting steel, comprising firing pre-mixed lignin and mineral filler in a ratio of 1: 0.2-2.0 at 760-960 ° C and an excess air coefficient of 0.2-0.8, characterized in that , in order to reduce the length of shrinkage defects in the head of the ingot due to the improvement of the heat-insulating properties of the mixture, perlite sand is used as a mineral filler, and before firing, the mixture is additionally dried at 105 - 400 ° C and an air excess coefficient of 0.1-0 , 3, Table! Indicators Content compositions mixtures mixtures “Τ ' ΞΤ 3 The drying temperature of the mixture before calcining hom, ° C 105-400 105-400 105-400 fifteen Excess coefficient No. of air during drying, d 0.1 0.2 oh s 20 . Mix firing temperature, ⁶ C 760 850 960 25 Excess ratio air during firing, d. 0.20 0.55 0.80 Table 2 thirty Indicators Values for mixes 1 ² .1 ³ 35 The bulk density of the mixture, kg / m ³ 90 80 1 1 1 ·* 1 o 1 o 1 - 1 1 40 The thermal conductivity of the mixture at 1000 ° C, W / m * k 0.11 0.09 0.13 45 The length of shrinkage defects,% of the length of the workpiece 14.5 12.5 14.5