RU2745006C1 - Method for obtaining carbon reductant - Google Patents

Abstract

FIELD: metallurgy.SUBSTANCE: invention relates to technologies for producing a briquetted carbonaceous reductant for producing metals and alloys by reduction melting in electric ore reduction furnaces. The method includes mixing carbonaceous materials in the form of fine fractions less than 5 mm and a binder, forming and drying a briquette, while the binder is used heat-treated wood pyrolysis resin at a temperature of 200-240°C with the following ratio of components, wt%: carbonaceous materials - 84- 88; wood pyrolysis resin - 12-16, after drying, high-temperature briquette firing is carried out at a temperature of 320-380°С.EFFECT: invention makes it possible to involve in the production of fines of carbonaceous materials, increases the mechanical strength of the obtained briquette and its technological suitability.1 cl, 7 ex

Description

Technology area

The invention relates to technologies for producing carbonaceous reductants for producing metals and alloys by reducing smelting in electric ore-reducing furnaces.

State of the art

Technical silicon and siliceous ferroalloys are obtained in ore-reduction furnaces, quartz or quartzites are used as the ore part of the charge, and carbonaceous materials of natural or technogenic origin are used as reducing agents. The main requirements for a carbonaceous reductant are the minimum content of undesirable impurities that pass into the final product during the melting process: for technical silicon, the content of iron oxides is limited, for silicon ferroalloys, the content of aluminum oxides is limited. The most common reducing agent used in the production of technical silicon is charcoal (Vengin S.I., Chistyakov A.S. Technical silicon. M., Metallurgy, 1972, 208 S.). The disadvantage of this technology is the large loss of the reducing agent. The latter is explained by the fact that charcoal is very fragile and when introduced into the charge and, especially, when it is overloaded, it is over-crushed and does not participate in the recovery process.

There is a known method of producing a carbon reductant from brown coal (SU 1406143, C10L 9/08, C10B 53/08, publ. 06/30/88), including its grinding, extraction of dull lithotypes from brown coal, drying and subsequent heat treatment up to 850 ° C, and for increasing the size and strength of the carbon reducing agent, emitting matte and semi-matte lithotypes with a lump size of 35-40 mm, drying is carried out at a speed of 12 deg / min and heat treatment at a speed of 2-3 deg / min. The disadvantage of this method lies in the complexity of obtaining the material due to the separation of the necessary fractions of coal according to petrographic characteristics and high energy consumption due to double heating for drying and heat treatment of the starting material.

A known method of producing a metallurgical briquette (patent RU 2655175, C10L 5/06, C10L 5/02, C10L 5/10, C10L 5/14, C10L 5/16, publ. 24.05.2018), obtained by mixing the starting components - carbon-containing material, which is a fines of coke grade MK-1, obtained by medium-temperature carbonization of brown coal, a two-component binder containing resin and the second component in the ratio (0.5-2): 1, and water with a temperature of 1 to 99 ° C, followed by pressing the briquette mixture and drying the formed briquette, and the binder contains starch as the second component, and the initial components are mixed in the following ratio, wt. %: carbon-containing material not less than 50; two-component binder 8-20; water is the rest. The disadvantage of this briquette is the increased content of undesirable impurities in the ash, which limits the use of this material as a reducing agent for the production of technical silicon.

Known coal briquette (patent RU 222007, C10L 5/02, C10L 5/06, publ. 27.06.2002), consisting of 100 wt. hours of coal fines, 1-5 wt. hours of quicklime and 7-15 weight. h. molasses. The briquette is intended for use in smelting and reduction processes. The disadvantage of this method for producing a briquette is in increased ash content, which limits its use in processes where the ash content in reducing agents is limited.

A known method of briquetting carbon reductants (patent RU 2669940, C10L 5/06, C10L 5/00, C10L 5/10, C10L 5/14, C10L 5/16, С01В 33/025, С22В 5/10, publ. 17.10.2018 g.), in which predominantly lignite or coal semi-coke (coke) is used, including mixing binder materials with semi-coke (coke), pressing and drying briquettes, and a combined binder containing high-temperature and low-temperature components is used as binders, and the carbon a reducing agent with a high-temperature component, then a low-temperature component is added, while as a high-temperature component, oil refining bottoms are used in the form of pyrolysis resin or catalytic gas oil in an amount of 25-30 wt. %, and organic substances are used as a low-temperature component in the form of a solution of gluten or molasses in an amount of 70-75 wt. %, when the ratio of the mixture of the combined binder and char (coke) is 1: 2. The disadvantage of this method is the use of components, the organic part of which does not withstand high-temperature processing and ignites, which reduces the quality of the briquetted reductant due to the low mechanical strength of 13.6-23.4 MPa to 3.7-5.4 MPa.

By its technical nature, by the presence of common features, this technical solution was adopted as the closest analogue of the claimed method for producing a carbonaceous reductant.

The basis of the invention is the task of involving in the production of fines of carbonaceous materials for their use as reducing agents in the production of metals and alloys.

The technical result is to increase the strength of the reducing agent.

Disclosure of invention

The technical result is achieved due to the fact that carbon materials are mixed in the form of fine fractions less than 5 mm and a binder, a briquette is formed and dried, while the binder is used heat-treated at a temperature of 200-240 ° C wood pyrolysis resin with the following ratio of components, wt. %:

carbon materials 84-88

wood pyrolysis resin 12-16,

after drying, high-temperature briquette firing is carried out at a temperature of 320-380 ° C.

The carbonaceous reductant may include natural coal and / or lignite and / or products of their beneficiation and / or heat treatment with a low content of impurities (upgraded lignite and / or bituminous coals and / or semi-coke of lignite and / or bituminous coals and / or charcoal) ...

The resin of wood pyrolysis, which has undergone heat treatment to remove moisture, light fractions of resin and creosote fractions, has surface activity, which favorably affects the strong bond of carbon components (Kiprianov A.I., The process of distillation of wood resin in tube furnaces, M., 1970) , and subsequent heat treatment of the briquette by removing volatile wood resin turns the resin into wood pitch, increases the strength and porosity of the briquette, which increases its technological suitability as a carbonaceous reductant.

Comparison of the proposed method for producing a carbonaceous reductant not only by the prototype, but by other analogs shows that:

- it is known to obtain a carbonaceous reductant by briquetting brown coal;

- there is a known method of briquetting carbonaceous reductants consisting of a carbonaceous part in the form of lignite or coal semicoke (coke);

- a briquette of coal fines is known for use in smelting-reduction processes;

- known to use molasses as a binder;

- known to use as a combined binder resin pyrolysis of oil and an organic component in the form of a solution of gluten or molasses;

- it is known to use as a combined binder a heavy oil pyrolysis resin and an organic binder in the form of potato starch.

The set of features, both known and unknown in their interconnection, allows you to obtain a technical result of a higher level, in comparison with the known ones, namely:

- higher mechanical strength.

Comparative analysis of known technical solutions did not reveal identical and equivalent features to the proposed solution, namely:

- obtaining a carbonaceous reductant using as a binder sludge resin pyrolysis of wood, which has passed the stage of temperature treatment at a temperature of 200-240 ° C;

- carrying out heat treatment of the briquette at a temperature of 320-380 ° C.

Thus, the proposed technical solution meets the criteria of the invention - inventive step and industrial applicability.

Implementation of the invention

The authors carried out experiments to obtain a carbonaceous reductant. Carbonaceous materials included low-ash natural bituminous and / or brown coals and / or products of their beneficiation and / or heat treatment (semi-cokes) with a low content of impurities, charcoal, carbonaceous materials were used in the form of fine fractions (less than 5 mm), which were the products of sieving reducing agents for target fractions of more than 5 mm, and a binder in the form of a heat-treated resin of wood pyrolysis, mixed, pelletizing, drying and heat treatment of the resulting briquette were carried out to convert the resin into pitch.

Examples of implementation of the method

Example 1. Concentrated coal, low-ash brown coal semi-coke, taken in a ratio of 1: 1, and a binder were mixed and formed a briquette. The content of carbonaceous materials was 95 wt. %, binder 5 wt. %. The briquette was dried and fired at a temperature of 300 ° C. After cooling, the strength was 19.7 MPa.

Example 2. Concentrated coal, low-ash brown coal semi-coke, charcoal, taken in the proportion: 1: 1: 1, and the binder were mixed and formed a briquette. The content of carbonaceous materials was 90 wt. %, binder 10 wt. %. After drying, the briquette was fired at a temperature of 300 ° C. After cooling, the strength was 19.2 MPa.

Example 3. Concentrated coal and charcoal, taken in a ratio of 2: 1, were mixed with a binder and formed a briquette. The content of carbonaceous materials was 88 wt. %, binder 12 wt. %. The briquette was dried and fired at a temperature of 320 ° C. After cooling, the strength was 24.9 MPa.

Example 4. Lignite semi-coke was mixed with a binder and formed a briquette. The char content was 86 wt. %, binder 14 wt. %. After drying, the briquette was fired at a temperature of 380 ° C. After cooling, the strength was 25.6 MPa.

Example 5 Concentrated coal and binder were mixed to form a briquette. The content of carbonaceous materials was 84 wt. %, binder 16 wt. %. The briquette was dried and fired at a temperature of 340 ° C. After cooling down, the strength was 24.8 MPa.

Example 6. Concentrated coal, low-ash brown coal semi-coke, taken in a ratio of 1: 1 and a binder were mixed and formed a briquette. The content of carbonaceous materials was 84 wt. %, binder 16 wt. %. The briquette was fired at a temperature of 450 ° C. After cooling, the strength was 17.4 MPa.

Example 7. Low ash semi-coke of brown coal and charcoal, taken in a ratio of 1: 2, the binder was mixed to form a briquette. The content of carbonaceous materials was 75 wt. %, binder 25 wt. %). The briquette was dried at a temperature of 120 ° C and firing was carried out at a temperature of 420 ° C. After cooling down, the strength was 18.6 MPa.

Analysis of experiments on obtaining lump carbonaceous reducing agents from materials of fraction 0-5 mm showed that the optimal ratio of carbonaceous material-binder is the mass ratio. %: carbonaceous material 84-88, binder 12-16 (examples 3-6). The optimal is the firing of the resulting reducing agent - at temperatures of 320-380 ° C (examples 3-5). High-temperature roasting increases the mechanical strength of the resulting pelletized reducing agent and increases its technological suitability.

Claims (4)

A method for producing a briquetted carbonaceous reductant, including mixing carbonaceous materials in the form of fine fractions less than 5 mm and a binder, forming and drying a briquette, characterized in that the binder is heat-treated at a temperature of 200-240 ° C wood pyrolysis resin with the following ratio of components, wt .%: carbon materials 84-88 wood pyrolysis resin 12-16, after drying, high-temperature briquette firing is carried out at a temperature of 320-380 ° C.