RU2113516C1 - Binding agent for nonfired agglomeration - Google Patents

Abstract

FIELD: metallurgy. SUBSTANCE: binding agent consists of metallurgic slag (5-90 wt %) and a substance containing active magnesium oxide. As the latter, magnesite firing dust, chemically pure magnesium oxide, or fired magnesite can be used. Agent is intended for use when preparing raw material for blast- furnace conversion. EFFECT: increased strength of pellets from different iron-containing materials. 2 cl, 2 tbl

Description

 The invention relates to metallurgy and can be used, in particular, when sintering finely dispersed materials for subsequent use in the metallurgical process.

 Known astringent, including magnesium oxide and water in the following ratio, wt.%: Magnesium oxide 85-88; water 12-15 [1].

 Its disadvantage is the low strength of non-calcined pellets, due to the low strength characteristics of the main hydration product - magnesium hydroxide.

 Known binders based on blast furnace slag - materials with potential binders [2].

 A disadvantage of pure slag binder is the very low strength of non-calcined pellets.

 The closest in technical essence and the achieved result is a binder for non-firing agglomeration, containing calcium-containing material, which is used Portland cement, or slag Portland cement, or Portland cement clinker and a substance containing active magnesium oxide [3].

 The disadvantages of this binder are the insufficient strength of non-calcined pellets obtained from a number of finely dispersed materials.

 The technical task of the invention is to increase the strength characteristics obtained by non-firing pelletizing pellets, as well as to create opportunities for regulation over a wide range of calcium and magnesium oxides in the slag of the subsequent processing, allowing you to choose its optimal composition for these components.

The problem is achieved in that the binder includes metallurgical slag and a substance containing active magnesium oxide, in the following ratio, wt.%:
Metallurgical slag - 5-90
Substance (material) containing active magnesium oxide - Rest
As a substance (material) containing active magnesium oxide, chemically pure magnesium oxide or calcined magnesite, or magnesite firing dust, is used.

 The main hydration products in the proposed binder are high-strength magnesium hydrosilicates synthesized by the interaction of a hydrated hardening activator and silicon oxide of the slag component. The individually taken ingredients of the proposed binder mainly hydrate slightly (slag) or do not give tumors with high strength properties (magnesium oxide).

The proposed binder is tested in laboratory conditions. Ore components were represented by sludge from gas purification of metallurgical plants: Nizhny Tagil (NTMK), Chelyabinsk (Chelyabinsk Metallurgical Plant) and Novokuznetsk (KMK), as well as calcined siderite ore of the Baikal ore department. Slag was represented by blast furnace slag of the same metallurgical enterprises and converter slag of Chelyabinsk Metallurgical Plant. As substances (materials) containing active magnesium oxide, chemically pure magnesium oxide was used, annealed in laboratory conditions for 2 hours at 700 ^° C, the magnesite of the Satka deposit, gas cleaning dust from the magnesite kiln of the Magnesite plant (hereinafter referred to as dust) firing magnesite). Active magnesium oxide in these substances was determined by OST 14 35-78. The number of unextinguished grains in them did not exceed 5%, the time and maximum temperature of quenching at optimal initial humidity (30-40%) were less than 20 min and 100 ^o C, respectively. The hardening results were similar for all three types of substances with active magnesium oxide and the following are the results with magnesite firing dust. Physico-chemical properties of the materials are given in table 1.

The experiments were carried out as follows. Take the original components, crushed to 100% cells. 0.1 mm (slag, calcined siderite ore, calcined magnesite) or in the original size (sludge) are mixed. Then the mixture is pelletized in drum pelletizers with a diameter of 400 mm with a water supply until pellets with a diameter of 14-16 mm are formed. Reinforce the pellets: 1) by steaming at a temperature of 90 ^o C for 8 hours (P); 2) by steaming followed by drying at a temperature of 200 ^o C (P + C) or natural for 7 days (P + EC); 3) holding in a humid atmosphere at 20-25 ^o C for 7 days (NT ₇ ) and 28 days (NT ₂₈ ) - normal hardening. The consumption of binders was 10% with a specific surface of ground slag 330-350 m ² / kg After hardening, the pellets were compressed.

Example 1. In accordance with the prototype take NTMK sludge, pelletize with the addition of a binder, consisting of blast furnace slag of the same plant and soda, taken at a ratio of components (wt.% 90:10. The strength of the pellets was, daN / ok: P 23; P + C 30; P + EC 18; NT ₇ 4; NT ₂₈ 4.

Example 2. The experiments were performed in accordance with example 1, but the mixture consisted of sludge and blast furnace slag KMK. The strength of the pellets was, daN / ok: P 4; P + C 6; P + C 6; P + EU 6; NT ₇ 6; NT ₂₈ 9.

Example 3. The experimental conditions of example 1 on a mixture of sludge and blast furnace slag ChMK. The strength of the pellets was, daN / ok; P 13; P + C 24; P + EU 10; NT ₇ 9; NT ₂₈ 16.

Example 4. The experimental conditions of example 1 on a charge of siderite ore and blast furnace slag ChMK, strength, daN / ok: P 37; P + C 71; P + EU 60; NT ₇ 8; NT ₂₈ 88.

 Example 5. KMK sludges are pelletized with the addition of blast furnace slag and magnesite firing dust taken at a ratio of components, wt.% 95: 5, i.e. outside the proposed composition. The strength of the samples after all hardening methods was greater than that of the prototype, but did not exceed 20 daN / okat.

 Example 6. In accordance with the proposed binder composition, KMK sludge was pelletized at a ratio of components (wt.%) Blast furnace slag: magnesite firing dust 90:10, that is, at the upper claimed limit for slag. The strength of the pellets was higher than with the binder-prototype, 2.5-4 times and significantly increased compared with the composition of example 5 (outside the claimed limits) in conditions of steaming and subsequent drying.

 Examples 7-10. The use of an astringent composition with a ratio of blast furnace slag: magnesite firing dust within the claimed interval allowed to increase, compared with the prototype, the strength of the pellets on all the materials studied in some cases several times.

 Example 11. KMK sludges were pelletized with the proposed binder, consisting of KMK blast furnace slag, from magnesite firing dust taken at a component ratio (wt.%) Of 5: 95, that is, at the lower slag declared. The strength of the pellets with all hardening methods remained 3-5 times greater than with the binder-prototype.

 Example 12. KMK sludge was pelletized with a binder consisting of blast furnace slag and magnesite firing dust taken at a component ratio (wt.%) Of 3: 97, that is, outside the declared limits. The strength of the pellets is lower than that of the binder in the claimed limits.

Example 13. The conditions of the experiment in example 1 on a mixture of sludge and converter slag Chelyabinsk Metallurgical Plant. The strength of the pellets was, daN / ok .: P 37; P + C 62; P + EU 46; NT ₇ 16; NT ₂₈ 26. It was comparable with these experiments 7, that is, the replacement of one type of slag (blast furnace) with another (converter) was not of fundamental importance and made it possible to obtain pellet strength significantly greater than the prototype in the claimed limits (see example 3). The result is explained by the fact that, regardless of the type of metallurgical slag, the mechanism of creating strength is maintained, based on the interaction of a substance containing active magnesium oxide with silicon oxide of the slag component. Therefore, other types of metallurgical slag, such as open-hearth slag (converter analog), cupola furnace, electrothermophosphoric (blast furnace analogs), electric steelmaking, production of low- and low-carbon ferrochrome, silica-containing slag of non-ferrous metallurgy, etc., can be used as part of the inventive binder.

 Examples 14-14. KMK sludge was pelletized with binder analogues (100% magnesite firing dust or 100% blast furnace slag). In all curing modes, the strength of the pellets was lower than in the claimed binder. It is also seen that the inventive binder allows you to get an effect that exceeds the total, which could have been additive from the addition of the effects of using magnesium oxide and slag (taking into account their shares in the binder). An additional effect of the use of the proposed binder is due to the formation of high-strength magnesium hydrosilicates, synthesized by the interaction of hydrated magnesium oxide and silicon oxide of the slag component. The results of comparative tests are presented in table. 2.

 Thus, the proposed binder allows to obtain pellets from various iron-containing materials with a stably high strength exceeding the strength of pellets with binders - analogues and prototype several times.

Sources of information
1. USSR author's certificate N 885177, cl. C 04 B 9/00, 1980.

 2. Royak S.M., Royak G.S. Special cements. M .: Stroyizdat, 1983.

 Magazine "Cement". N 11, 1990, p. 5-13.

Claims (1)

1. A binder for non-firing agglomeration, including calcium-containing material and a substance containing active magnesium oxide, characterized in that metallurgical slag is used as the calcium-containing material and these ingredients are taken in the following ratio, wt.%:
Metallurgical slag - 5 - 90
Active Magnesium Oxide Substance - Rest
2. The binder according to claim 1, characterized in that as a substance containing active magnesium oxide, magnesite burning dust or chemically pure magnesium oxide or calcined magnesite is used.

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