CN1252228C

CN1252228C - Method for improving thermal property of coke

Info

Publication number: CN1252228C
Application number: CN 01139280
Authority: CN
Inventors: 张群; 杨俊和; 吴信慈; 冯安祖; 金宝; 史美仁; 程乐意; 钱湛芬; 许梅郎
Original assignee: Baoshan Iron and Steel Co Ltd; Shanghai Institute of Technology
Current assignee: Baoshan Iron and Steel Co Ltd; Shanghai Institute of Technology
Priority date: 2001-12-28
Filing date: 2001-12-28
Publication date: 2006-04-19
Anticipated expiration: 2021-12-28
Also published as: CN1428406A

Abstract

The present invention provides a method for improving the thermal property of coke. Element boron and boron system compounds are added to serve as negative catalysts which can be added into mixing coal and can also be added ito the coke. The thermal property of coke can be effectively improved by the method.

Description

Method for improving thermal property of coke

Technical Field

The invention relates to a method for improving the thermal property of coke, in particular to a method for improving the thermal property of coke by adopting a negative catalyst.

Background

The thermal properties of coke are mainly referred to as the reactivity and post-reaction strength of the coke. In blast furnace iron making, coke plays the roles of a breathable material column framework, a reducing agent, a carburizing agent and a heat source, and carbon in the coke reacts: reduction of Fe to CO₂O₃And Fe₃O₄At the same time, the coke is also deteriorated, and the permeability of the blast furnace material column is reduced. The blast furnace practice shows that the thermal property of coke is related to many blast furnace process parameters such as the air permeability of the material column, air flow distribution, material collapse and slip, fuel ratio, tapping operation times and the like. The quality of the thermal property of the coke is the key to reduce the iron-making cost if the blast furnace can be greatly injected.

The properties of coal are the decisive factors of the thermal properties of coke, and the traditional coking coal blending technology always emphasizes the blending of rich coal and coking coal with medium deterioration degree and strong caking property so as to improve the thermal properties of coke and reduce the deterioration of the coke in a blast furnace. The problem currently faced, however, is that such coals are expensive, have limited resources, and are exhausted throughout the day. The coke oven has low heat efficiency and serious pollution, and the increasingly strong environmental protection call forces many factories and mines to develop new coking processes, such as dry quenching, molding coal, coal preheating and the like, so as to improve the coke quality, reduce the environmental pollution, prepare weak caking coal or non-coking coal more and reasonably utilize high-quality coking coal resources. However, the adoption of the above process will increase the cost input greatly, which determines that the coke cost is the big end of the iron (or even steel) making cost.

In recent years, foreign scholars have sought a new, efficient and industrially feasible method for improving the thermal properties of coke by post-treating the coke to improve its thermal properties, m.ogawa, m.miyawaki andtuyuuchi (113th ISIJ meeting of April, 1987, feature No. S-62) conducted a study of improving the thermal properties of coke by dropping hot road coke oil on the coke and heating to deposit the carbon produced by cracking on the coke to improve the reactivity of the coke (decrease coke CO)₂The rate of oxidation reaction) increases the thermal strength of the coke, thereby improving the thermal properties of the coke, but prevents industrialization thereof due to the generation of a large amount of soot by cracking the tar.

Us patent No. s.5486216 describes a method of depositing carbon on the outer surface of low-quality coke by cracking hydrocarbons using CVD (vapor phase pyrolysis deposition) technique, and the generated carbon particles are filled in the pores of the coke to form a dense and hard carbon layer. The method reduces reaction area, and physically blocks CO₂The reaction, which is combined with dry quenching, is complicated to operate because of the introduction of combustible hydrocarbons in the dry quenching furnace, and the method is very dangerous because of the possibility of explosion if air leaks in.

The Su Union patent SU1775462 adds p-benzenediol into the charging coal, 10% of lignite semicoke and weak caking coal replace strong caking coal for coking, the coke strength is increased, the method has great change to the coking process system, and the industrial implementation is difficult.

Disclosure of Invention

The invention aims to provide a method for improving the thermal property of coke by using a negative catalyst. The method of the invention is to reduce coke from the chemical perspectiveC and CO in carbon₂Thereby improving the thermal properties of the coke.

The negative catalyst can reduce the reaction speed and hinder the reaction, is widely applied to the chemical industry, and is also widely regarded in the fields of material science and energy science, such as a retarder of carbon material antioxidant reaction and the like.

The method for improving the thermal property of the coke is to add a negative catalyst, wherein the adding amount of the negative catalyst accounts for 0.02-2% of the total weight of the coal or the coke.

The negative catalyst is boron or boron compound.

The boron compound is boric acid or borax or B₂O₃And the like.

The negative catalyst is added into the coal blending or added into the coke for mixing.

Carbon is a substance (element) which is chemically very stable in nature and chemically inert at ordinary temperatures and in ordinary environments, but is extremely reactive with oxidizing gases at higher temperatures (e.g., in blast furnaces) because the planes of the carbon network in the graphite-state crystal are spatially finite and they end up at grain boundaries, dislocations or surfaces, so that there is always a certain number ratio of edge carbon atoms in the plane of the carbon network₂Eventually etch pits will form on the plane of the carbon web. CO of boron-based compound to coke₂The solution loss reaction has a negative catalytic effect and inhibits C and CO in the coke₂Reacting to improve the thermal properties of the coke.

Boron compounds such as boric acid, borax, B₂O₃Etc., elemental boron can improve the thermal properties of the coke. Elemental boron has the best effect of improving the thermal properties of coke. This is because the outermost layer of boron atoms has 3 electrons, which are called SP²Three hybridized covalent bonds form a coplanar structure and are mutually connectedAt 120 deg., in exactly the same way that carbon atoms in the plane of the carbon network in graphite form bonds. Boron has an atomic radius of 91pm, which is very close to the atomic radius of 90pm of carbon, and can form substitutional solid solutions in carbon, and can also be intercalated as a compound between the layers of the graphite crystal. In addition, B is formed after oxidation of B₂O₃The carbon solution is covered on active sites of the coke, the carbon solution reaction is physically hindered, in addition, the пelectronic distribution of C atoms is changed by the existence of B, the analysis effect of CO is reduced, the carbon solution reaction speed is reduced, and the graphitization is promoted due to the addition of B, so that the total amount of the active sites such as edge carbon atoms and the like is reduced, the carbon solution reaction of the coke is inhibited, and the thermal performance of the coke is improved.

Various methods are used to make the coke contain boron, the existence of boron can improve the thermal property of the coke, and the method of adding the negative catalyst into the coke can adopt a coal blending method or an impregnation method.

As shown in FIG. 1, the reactivity (CRI) of coke added with negative catalyst is significantly lower than that of coke without negative catalyst, and the reactivity continues to decrease as the amount of negative catalyst added increases, indicating that the addition of negative catalyst causes coke and CO to form₂The reactivity of the reaction decreases. As can be seen from FIG. 2, the coke with added negative catalyst has a significantly better post-reaction strength (CSR) coke than the coke without added negative catalyst and is also negatively catalyzedThe increase in the amount of the additive increases the strength of the coke after the reaction.

1. After the method is used, the ratio of the strongly-bonded coal in coal blending and coking can be reduced, so that precious strongly-bonded coal resources can be saved, and the coking cost can be reduced.

2. After the method is used, the thermal property of the coke can be greatly improved, the guarantee is provided for the large coal injection, and the iron-making cost is reduced.

3. The method of the invention is also expected to be used in other industries, for example: carbon materials, energy sources, and the like.

Drawings

FIG. 1 is a graph of the effect of a negative catalyst on reactivity

FIG. 2 is a graph of the effect of a negative catalyst on the intensity of coke after reaction

FIG. 3 is a flow chart of adding a negative catalyst by a coal blending method

FIG. 4 is a flow chart of adding negative catalyst by coke impregnation

Detailed Description

Example 1

Method for adding negative catalyst by coal blending method

As shown in FIG. 3, the apparatus can be used to add a negative catalyst to the blended coal. Coal in the coal yard enters a coal blending tank after being crushed for the first time, is mixed with a negative catalyst, passes through a secondary crusher and enters a coal tower.

The coke added with the negative catalyst is subjected to a thermal property test, and the result shows that after the element boron is added, the CRI of the blended coal with better quality is reduced to 12.3% from 21.1%, the CSR is increased to 78.3% from 66.8%, and the CRI and the CSR of the blended coal with poorer quality are respectively reduced to 15.2% from 32.8% and 74.5% from 50.7%; therefore, after the coking coal is blended with the negative catalyst for coking, the thermal property of the coke is greatly improved.

Example 2

Method for adding negative catalyst by coke impregnation method

As shown in fig. 4, a flow diagram for adding negative catalyst for the coke impregnation method. The wet quenching is to quench red hot coke in a quenching tower by water, and the facility mainly comprises a quenching tower 1, a circulating pump 2, a powdered coke sedimentation tank 3, a clean water tank 4 and the like. The negative catalyst is directly added into a clean water tank 4, and is pumped into a coke quenching tower 1 by a circulating pump 2, the coke quenching process is completed at the same time of coke quenching, and coke powder is precipitated by coke quenching water through a precipitation tank 3 and then enters the clean water tank 4 for reuse.

The coke is impregnated with negative catalyst by dipping the cut coke in a negative catalyst solution with a certain concentration, measuring the amount of the negative catalyst absorbed in the coke after the water is evaporated,and the thermal properties of the coke. For example, adding B to coke₂O₃Then, the reactivity and strength of coke are improved from 29.2%, 56.9% to 21.2%, 68.1%. For the Bao steel coke, the reactivity is 23.77%, the strength after reaction is 70.37%, and the thermal property is improved after the Bao steel coke is dipped in the negative catalyst boric acid: the reactivity is 18.2%, the strength after reaction is 77%, and the thermal property of the coke can be greatly improved after the coke is impregnated with the negative catalyst, so that the thermal property of the coke can be greatly improved by adopting the method provided by the invention.

Claims

1. The method for improving the thermal property of the coke is characterized in that a negative catalyst is added, and the addition amount of the negative catalyst accounts for 0.02-2% of the total weight of the coal blending or the coke.

2. The method for improving the thermal properties of coke according to claim 1, wherein said negative catalyst is elemental boron or a boron-based compound.

3. The method for improving the thermal properties of coke according to claim 2, wherein the boron compound is boric acid or borax or B₂O₃。

4. The method of improving the thermal properties of coke of claim 1 wherein the negative catalyst is added to the coal blend or to the coke.