SU1776253A3 - Method for production of building materials from high-basicity metallurgical slags - Google Patents

Description

The invention relates to the building materials industry and can be used to obtain aggregate and a hydraulically active binder from waste metallurgical production.

A known method of producing slag melt by mixing highly basic blast furnace slag with a corrective additive. Corrective additive is introduced at a temperature of 450-500 °. It contains 32-35% silica sand, 9-11% magnesite and 2.5-3.0% sodium-containing substances by weight of slag. This method is unsuitable for slag, disintegrating into powder by a silicate mechanism, since this decay occurs at a temperature of 1480 °. and also unsuitable for all highly basic slags, because at a temperature of 450-500 ° their viscosity is so high that eliminates the possibility of a uniform distribution of corrective additives in the slag mass.

Closest to the invention in technical essence and the achieved result is a method for producing slag melt, adopted as a prototype, where quartz sand is added to liquid slag I. I

The use of natural raw materials - sand as an additive entails the need to organize a special redistribution for sand drying and significant energy costs for drying, since natural sand contains moisture, and in the molten slag to prevent explosion is not allowed to supply wet material, in addition, it is economically disadvantageous, because the cost of natural sand is 2-6 rubles / t, plus the cost of energy for drying 1-5 rubles / t and is technologically inefficient due to the low reactivity of sand, which even in a small ratio with slag (for example 1:10) is not able to dissolve in it and remains cool in the form of unreacted inclusions.

1776253 AZ

The aim of the invention is to reduce the cost of building material and increase its strength.

This goal is achieved by the fact that silica waste from foundry with silica content> 70% in the amount of 5-30% by weight is used as an additive, and, depending on whether they want to obtain a binder or aggregate, liquid slag with the additive after aging subjected to rapid cooling by granulation, or natural cooling in air.

The method is suitable for processing all highly basic slags, including open-hearth slag, electric furnace, converter and blast furnace. It eliminates the danger of silicate decomposition of slag and eliminates the decay as a result of late hydration of lime, because binds it to calcium and magnesium silicates. They receive a binder of hydraulic hardening, or aggregate, suitable for use not only in road construction, but also in concrete for civil and industrial construction, as well as in the production of various small-sized building materials.

The additive is introduced into the liquid-liquid slag after the completion of the main metal production process, and the additive can be introduced into the loading hole of the furnace itself, into the slag stream during its discharge, and also directly into the slag bowl or slag. The appropriate length of the slag aging period after the introduction of the foundry waste additive before pouring from the slag bowl for 10-60 minutes. However, the duration of the retention of the obtained slag fluid state, necessary for complete discharge and for effective granulation, exceeds 2 hours. To increase the uniformity of distribution of siliceous additives in the volume of slag in the slag bowl, melt is bubbled. Bubbling of the slag is carried out using oxygen blasting either during the introduction of the silica component, or after its introduction. As siliceous waste foundries use "burnt earth. This term means both coarse-grained wastes of foundry molds and fine dust generated during cleaning of castings and removed, as a rule, by aspiration. For higher efficiency of the proposed method, additives - hardening activators can be added to the mixture of slag and burnt earth.

For the implementation of the method is suitable for any burnt earth:

on a clay binder - the presence of aluminosilicates in the binder has a positive effect on increasing the hydraulic activity of the product;

on liquid glass - an alkaline medium increases the solubility of SiO2, 'on an organic binder - organic matter at a temperature of liquid slag (13001800 °) burns out and does not adversely affect the properties of the product.

PRI me R 1. Modification of liquid slag to obtain coarse aggregate for concrete and for road construction.

They use ferrovanadium-electric steel-smelting slag of the Chusovsky Metallurgical Plant. In its original form, this slag cannot be used as a coarse aggregate, because upon cooling in air, it disintegrates into powder due to the phase transition of calcium orthosilicate from the β modification to the γ modification, which proceeds with a sharp decrease in density.

The siliceous additive is introduced into liquid slag in two versions:

into an electric furnace - through a loading hole, followed by mixing with a pusher;

in a stream - during the discharge of slag from the furnace into the slag. .

As an additive, burned earth (according to the invention) and natural sand (according to the prototype) are used. The SiO2 content in both additives was 92%.

After natural cooling in air, the slag is crushed on a jaw crusher with a slit width of 40 mm. The crushing product is checked by the standard method for the stability of the structure against decay, for the strength and presence of the decay product / for C2S / and unreacted silica additive. Test results see table. 1.

As follows from the table. 1. the proposed method allows the use of burned earth in an amount of 5-30% by weight of slag to almost completely eliminate the decay of slag. A higher percentage of the content of the additive is impractical because SIO2 remains unreacted. It is not possible to achieve the same performance using natural sand. With equal dosages of silica additives, crushed stone strength, determined by the crushability grade, is higher in the case of burning earth.

PRI me R 2. Modification of liquid slag to obtain coarse aggregate for concrete and for road construction.

The open-hearth slag of the Amurstal metallurgical plant (Komsomolsk-on-Amur) is used. In its original form, this slag cannot be used as a coarse aggregate in compositions with a hydraulic binder, because slag contains baked lime, and, in particular, periclase, which in the presence of moisture in the pores of concrete leads to the destruction of the structure.

A siliceous additive is injected into the liquid slag during a stream - during the discharge of slag from the furnace into the slag bowl.

As a silica additive according to the proposed option, 2 types of foundry waste are used:

1. with a content of SiO2 - 70%

2. with a SiO2 content of ~ 67% according to the prototype, natural sand with a SiO2 content of ~ 70%. After naturally cooling in air, the slag is crushed into. jaw crusher with a slot width of 40 mm. The crushing product is checked by the standard method for the stability of the structure against decay, for strength and for the presence of free lime (CaO. MdO) and unreacted additives. The test results are given in table. 2.

In accordance with the data table. With a 2.5% addition of foundry waste when SiO2 = 70% is contained in it, it is possible to bind the free oxides CaO and MgO into silicates and thereby avoid their subsequent decomposition upon contact with water. A decrease in this additive does not ensure complete binding of periclase and, accordingly, does not completely eliminate the decomposition of the resulting product. With the introduction of a 5% additive with a lower content of S1O2, it is not possible to completely bind all the free lime, which also entailed the presence in the aggregate of a certain amount of particles capable of decay upon contact with moisture.

Siliceous additive according to the prototype, even with a significant value does not provide complete elimination in the slag decay.

Example Z. Modification of liquid slag to obtain cementitious hydraulic hardening.

Converter slag of the Novolipetsk Metallurgical Plant is used. In its original form, slag cannot be used as a binder, because almost inert.

Siliceous additives are fed into the slag stream when it is drained from the converter into the slag bowl. After 30 minutes, the liquid slag is subjected to granulation, and then grinding by ball mill on a specific surface of 4000 cm ² / g

As an additive, burned earth with SiO2 = 75% content of the foundry of the Novolipetsk Metallurgical Plant (according to the proposed method) and natural sand with SiO2 content = 75.5% (according to the prototype) are used.

Samples of beams are made from crushed slag, which harden in three different modes:

1) in an autoclave at a pressure of 9 atm and a temperature of 173 ° C for 14 hours;

2) & a steaming chamber at atmospheric pressure and at a temperature of 95 ° C for 6 hours;

3) in a chamber above water at atmospheric pressure and a temperature of 18-20 ° C for 28 days.

After curing, the samples are tested for strength in bending and compression. The test results are shown in table.Z.

As follows from the table. 3. The use of siliceous foundry waste compared to natural sand significantly (up to two times) increases the physico-mechanical properties of modified slag as a binder.

Modification of highly basic slag by siliceous waste from the foundry, in addition, contributed to an increase in the duration of slag storage. fluid state up to 2-4 hours, which allows to introduce the technology of granulation of steelmaking slag, which is currently not produced due to their high viscosity and quick solidification.

The use of metallurgical waste, in addition to the direct effect of obtaining building materials, can improve and is a cost-effective enterprise.

Instead of burnt earth, acidic ash, slag, and fireclay bricks made of fireclay or dinas can be used. ''

Claims (5)

Claim 1. A method of producing building materials from highly basic slags of metallurgical production by introducing a silica-containing additive into the slag melt, mixing the melt and then cooling it, characterized in that, in order to reduce the cost of the building material and increase its strength, silica waste of foundry is used as an additive production with a silicon oxide content of £ 70% in an amount of 5-30% by weight. 2. The method according to claim 1, with the fact that in the capacity of siliceous waste foundry use burnt earth. - 3. The method of pop. 1, characterized in that as a silica waste foundry use the battle of refractory bricks. 4. The method according to claims 1 and 2, characterized in that, in order to obtain a hydraulically active binder, the molten slag with the additive is granulated and then ground. 5 5. The method according to PP. 1 and 2, which is distinguished by the fact that, in order to obtain a filler, the slag melt is naturally cooled in air. Table g Type of additive K-βο to Conditions of administration Modified Slag Properties pp bavok, ί additives by mass Loss Brand by Availability in slag slag masses, strength (for now ? ^s 2 ⁸ of freedom zat.dro (product S1Q, bimoty) decay) (no tirov · additive) Proposed method 1 Burnt earth 5 * To the oven with stirring 5 minutes" 4.2 Dr25 . a + 2 18 0 Dr15 . - 3 _and p. thirty _n _in 0 Dr15 - B 18 In stream 0 Dr15 . - - 5 a"*'·. '' thirty 0 ΛΡ15 - 6 ·· "· 32 - In the oven with 0 Lr15 - + by spraying for 5 minutes Prototype method 7 Natural apiary 18 _t To the oven with stirring for 5 minutes 38 Lr35 + + 8 18 To the oven with stirring 25 min 22 Lr25 + + 9 18 In the stream 53 Dr45 + 10 l 33 To the oven with mixing • 5 min. 29th Lr25 + eleven 33 To the oven with stirring 25 min '5. Dr15 . + 4· 12 33 .To the stream 4l Dr35 + + Table D ig '' Type of additive V Amount of additives, $ by weight of slag Modified Slag Properties Mass loss (%) during decay test Strength grade (in terms of fraction of the bridge) Availability in spar CaO MgO Free Si0 ₄ (unreacted additive) 1 2. . . s ... . 4. 5 6 7 8 5 According to the proposed method ; 1 . Burned land with content ♦ sio, - 70X 5 0 Dr15 - - - 2 fifteen 0 Lr15 - - + 3 thirty 0 Dr15 - + 1) Ji 3 5.8 Lr35 - ♦ - Continued tabd, , 2 GT | L.5 ..... J 6 1 7 J..8 .................. 5 Burned land with content SiQ) j = 67Z 5 · 6.7 Lr35 + 4- According to the prototype 6 Natural »sand with SiO _x content» 70Z fifteen 8.4 Lr35 + + + Table? south pp Type of additive K-e additives,% by weight of slag The strength of the samples, MPa After 29 days of hardening over water After steaming After autoclaving compression | bend squeeze | bend compression | bend According to the proposed way 1 Burnt earth 5 15.0 3.8 13,2 2.6 23.5 5.1 2 20 62.0 6.7 30.5 5.9 60.0 8.2 3 _n_. thirty 60.1 6.3 29.7 5.2 56.0 7.7 1" 3 6.7 1,5 5.1 12 16,2 3.3 5 32 30,2 '57 26.0 5,0 38,0 6.3 According to the prototype 6 Natural sand 20 20.1 6.1 15,2 28.0 6.9