CN1040338C

CN1040338C - Technology for dephospyhorizing and forced desulfurating in cupola

Info

Publication number: CN1040338C
Application number: CN95105239A
Authority: CN
Inventors: 布禾
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-05-05
Filing date: 1995-05-05
Publication date: 1998-10-21
Anticipated expiration: 2015-05-05
Also published as: CN1130212A

Abstract

The present invention relates to technology for dephosphorization and forced desulfuration in an iron melting furnace. A novel solvent is utilized to replace the CaCO3 (calcium carbonate) solvent in the original technology on the basis of the traditional technical method. The technical method of the present invention can be used for fully utilizing high-phosphorous and high-sulfur pig iron to cast iron castings conforming to the Chinese standard. The technical method not only can develop a large number of the resources of high-phosphorous and high-sulfur pig iron in China, but also can reduce the casting cost and enhance the economic benefit and the competitive power of products.

Description

Dephosphorization and intensified desulfurization process in cupola furnace

The cupola furnace is a pre-process equipment used for converter steelmaking without blast furnace molten iron and a smelting equipment in the casting industry.

The conventional process cannot dephosphorize in the cupola because the cupola is a reductive smelting device and dephosphorization is an oxidation reaction. However, the metallurgical reaction process of the cupola furnace does not always dephosphorize, and as shown in the first and second figures, there is an oxidation zone near the tuyere where CO is present₂Rapidly increasing and reaching the maximum value, having thermodynamic and kinetic conditions for dephosphorization, and carrying out dephosphorization reaction by an oxidation zone: 2(P) + 5(FeO) + 4(CaO) =4 (CaOP)₂O₅) +5Fe [ 1]is only reduced in the iron storage zone, i.e. the reduction zone: CaOP₂O₅＋SiO₂+5C→CaOSiO₂The +2P + CO ↓ (2) reduces the phosphorus removed to the molten iron, and the final result is that the phosphorus cannot be removed.

The invention aims to replace the traditional flux CaCO with a new flux on the basis of the traditional process₃(CaO) to effect dephosphorization in the cupola. The invention utilizes BaCO₃(BaO) is a fusing agent and replaces CaCO solvent in the traditional process₃(CaO) to stabilize the formation of CaO in the oxidation zoneThe compound of (a) to (b),

the reaction is as follows;

and is not reduced, or not reduced entirely, in the reduction zone. Different parts in the cupola furnace are in different thermodynamic states, there is an oxidation zone near the tuyere, and there is free oxygen in this zone. When the tuyere is gradually far away, the oxidation zone is cut off because the carbon-oxygen reaction continuously consumes oxygen and finally consumes oxygen. The other part of the oxidation zone is a reduction zone and a preheating zone, the free oxygen in the reduction zone is exhausted, red hot coke exists, and the gas phase composition is mainly controlled by CO through a delta-delta reaction. The gas phase composition of the oxidation zone is CO and CO₂、O₂Etc., as shown in fig. 1 and 2. The gas phase composition and the temperature curve are adapted, CO is rapidly increased and transported to the maximum value at the position of 300mm away from a tuyere of the cupola furnace, the thermodynamic and kinetic conditions of dephosphorization are provided, the temperature of an oxidation zone is between 1200 ℃ and 1550 ℃, and the ideal temperature for the dephosphorization reaction which takes the thermodynamic and kinetic conditions into consideration. B is_aCO₃The natural mineral of (barium carbonate) is witherite if it is mixed with B_aSO₄(barium sulfate) coexists and must be replaced by B_aCO₃Is the main component because only B_aCO₃Can remove phosphorus (P) and sulfur (S); and B_aSO₄P, S cannot be removed. B is_aCO₃(B_aO) to C_aCO₃(C_aO) has much greater affinity for P, S, and therefore, in the reduction zone, C is used_aCO₃(C_aO) is generated as a fluxIs reduced again into the molten iron, whereby B_aCO₃(B_aO) is a flux, and thus the compound produced is not reduced, so B is used_aCO₃Can realize dephosphorization in an iron melting furnace as a solvent. But from B_aCO₃And C_aCO₃In terms of the molar equivalent ratio of (a),

1molB_aCO₃/1molC_aCO₃197.341g/100.089g is 1.97 so, B_aCO₃In the case of fluxes, useThe amount must be C_aCO₃1.97 times of the total weight of the powder.

The invention has the advantages that the resource of high-phosphorus and high-sulfur pig iron can be fully utilized in the casting industry, so that the cost of the iron casting is reduced, and the economic benefit is improved.

The first and second figures are gas phase distribution diagrams. As can be seen from the figure, the gas phase composition curve is adapted to the temperature curve, and CO is arranged at the position of 300mm away from the tuyere of the cupola furnace₂To a maximum value.

In the process of the invention, the alkalinity R of barium_BaThe specific value of (A) depends on the P, S content of the charge. To obtain B_aThe effect of O removal P, S ability was also tested in a new city called Haoyasty by a new foundry, who purchased a portion of dolomitic pig iron (i.e., high P, high S pig iron), which was first subjected to P, S chemical composition analysis, 001^#、002^#Phosphorus contents of 0.047 and 0.654; the sulfur content is 0.046 and 0.063 (see appendix two), and meets the phosphorus and sulfur content provided by dolomite iron ore (see appendix one). The production process place of the factoryBy using 50% pig iron and 50% recycled iron in the metal charge, the plant, in order to avoid unduly affecting the quality of the product, had originally incorporated 1/5 dolomite pig iron (i.e. high phosphorus, high sulfur pig iron) into the cast pig iron portion of the charge, and its product 003^#The phosphorus content was 0.486; the sulfur content was 0.600 (see appendix two). For the first experiment: the pig iron in the furnace burden is completely dolomite pig iron, the flux is tested by taking limestone and witherite which respectively account for 50 percent, and the phosphorus content is 0.476; 0.487; 0.442; 0.454; the sulfur content was 0.190; 0.206; 0.122; 0.114; it can be seen that C is used in total_aCO₃(limestone) is not too different in effect, and there is no significant effect of removing P, S (see annex three 004)^#、005^#、006^#、007^#The assay result of (a). In the second experiment, the fluxing agent is made of witherite (the witherite contains B)_aCO₃64.61%; containing B_aSO₄14.16 percent), adding 9Kg of witherite according to 100Kg of iron (the pig iron part in the charging material is all dolomite pig iron), and obtaining the phosphorus content of the iron casting to be 0.249; 0.261; 0.246; 0.220; 0.244; 0.213; the sulfur content was 0.168; 0.183; 0.174; 0.266; 0.194; 0.244 (see appendix four 008)^#、009^#、010^#、011^#、012^#、013^#The assay result of (a). The third time of flux decrement experiment, the pig iron part still uses 100% dolomite pig iron, the flux uses witherite completely, uses 7.5Kg witherite according to 100Kg ironFlux, resulting in a phosphorus content of 0.259; 0.294; 0.283; 0.247; 0.313; 0.262; the sulfur content was 0.240; 0.220; 0.230; 0.244; 0.204; 0.229 (see annex five 014)^#、015^#、016^#、017^#、018^#、019^#The assay result of (d). The conclusion is that the phosphorus and the sulfur are increased. For this reason, two experiments were carried out in which 10Kg of witherite and 15Kg of witherite were added to 100Kg of iron charge, respectively, and when 10Kg of witherite was added, the phosphorus content was 0.255 and the sulfur content was 0.112; when 15Kg of witherite is added, the phosphorus content is 0.232 and the sulfur content is 0.0917 (see the accessory six 020)^#、021^#). From the above results, it can be seen that B_aCO₃The affinity of the flux to phosphorus and sulfur is much larger, the compound generated in an oxidation zone is more stable, the reduction zone is not easy to reduce, and phosphorus and sulfur can be removed in an iron melting furnace. For the raw materials charged into the furnace in this experiment, it is appropriate to add 10Kg of witherite, i.e., the ratio of charged iron material to the amount of witherite added is 10: 1. It can also be seen that the theory and experiment of strengthening desulfurization in the furnace are the same as the dephosphorization in the furnace.

Claims

1. A process for removing phosphorus and sulfur in iron smelting furnace features that barium carbonate (B)_aCO₃) The solvent is calcium carbonate (C)_aCO₃) Is 1.97 times of the flux.

2. A process according to claim 1, wherein the flux barium carbonate (B) is used_aCO₃) The natural mineral of (A) is B_aCO₃As the main component, barium sulfate (B) can be added_aSO₄) Symbiotic witherite.