CN87104601A - high purity ferrosilicon and production method - Google Patents

Abstract

The invention relates to high-purity ferrosilicon and its production method. It uses selected quartz stone, petroleum coke, and silicon steel scrap as raw materials to reduce and smelt ferrosilicon in a submerged arc furnace. The coke particle size is 0-10mm. The ratio of raw materials is quartz stone: petroleum coke: silicon steel scrap = 100:40-55:5 -55. Quartz contains SiO ₂ >98.0%, Al ₂ O ₃ <0.03%, CaO <0.01%, and the sum of other impurities (except iron oxide) <0.02%. This ferrosilicon can be used to smelt high grade non-oriented silicon steel, oriented silicon steel and low alloy steel.

Description

High-purity silicon iron and production method thereof

The present invention belongs to the field of metallurgy, and the high-purity ferrosilicon product is mainly used for smelting high-grade oriented silicon steel, non-oriented silicon steel, low-alloy steel, etc., and the method is suitable for various submerged arc furnaces for smelting ferrosilicon.

The smelting ferrosilicon in Japan, America, Norway and other countries adopts silica plus metallurgical coke (+ petroleum coke plus charcoal plus coal and the like) plus steel scrap (or iron ore) to be reduced in an ore-smelting furnace, and a multi-element slag absorption method is used outside the furnace to remove partial impurities, so that the process is complex. All domestic manufacturers produce ferrosilicon, the method is to use silica, metallurgical coke and the like and steel scraps to reduce in a submerged arc furnace, a few manufacturers remove impurities by a multi-element slag absorption method, and the obtained product has high impurity content and is not suitable for smelting high-grade silicon steel. The traditional compounding method is that the ratio of silica to coke to steel scrap is 100: 48-56: 26, and the silica contains SiO₂More than 97 percent of the coke can be used, the granularity of the coke is 5-18mm, and the steel scraps are common carbon steel scraps. The defects are that the metallurgical coke ash content is high, the common steel scrap generally contains 0.4-1.4% of Mn, and the contents of Cr, Ti and V are also high, so that the quality of the silicon iron is difficult to ensure, the coke granularity is large, the surface area is small, and the reduction reaction time is long.

The invention aims to overcome the defects of the traditional method, and the high-purity silicon iron is produced by selecting proper raw materials and process conditions and is used for smelting high-grade silicon steel and the like.

The invention is realized by the following method, quartz stone plus petroleum coke (or petroleum coke plus a small amount of other carbon) plus silicon steel scrap are selected and reduced in an ore-smelting furnace, the granularity of the petroleum coke is 0-10mm, and the optimal granularity is 0-5 mm. The proportion of charging material is quartz stone, petroleum coke and silicon steel scrap is 100: 40-55: 5-55, and the proportion takes the fixed carbon content as the reference quantity. The chemical composition (weight) of the quartz stone is required to be SiO₂＞98.0%，Al₂O₃Less than 0.03 percent, less than 0.01 percent of CaO and less than 0.02 percent of the total of other impurities except ferric oxide. The impurity content of the obtained high-purity silicon iron product can be controlled in the following range;

TABLE 1

Si and Fe are effective elements, and the proportion is adjusted according to the use requirement. If necessary, according to the change of the required amount of individual elements, chlorine gas can be respectively introduced into the discharged liquid product for 20-40 minutes and 20 kg, or oxygen gas can be respectively introduced into the discharged liquid product for 30-40 minutes and 5 kg, or water gas (H)₂+H₂O) 20-40 min, 5 kg.

The smelting operation of the invention is the same as that of the ferrosilicon produced by the common submerged arc furnace method. The ore-smelting furnace is electrified to raise the temperature and bake to over 1000 ℃, mixed materials are gradually added into a hearth until the hearth is full, then the charge level is maintained, the furnace is stoked and perforated as required. Continuous reduction smelting, intermittent blowing-in, first discharging time is longer, and then the regular discharging time is different along with the capacity. Normally, no external refining is needed, and if the impurity of the discharged product exceeds the standard due to the slightly higher impurity of the ore, a small amount of chlorine, oxygen or chlorine-oxygen can be introduced according to the impurity components to carry out the external liquid refining. Sampling, analyzing, casting ingot, crushing and packaging.

FIG. 1 is a flow chart of the process for producing high-purity Si-Fe by this method.

The method is carried out on a 4000KVA submerged arc furnace in a test mode, and the main parameters are as follows:

furnace type: open fixed ore-smelting furnace

The voltage used: 80-110V

Outer diameter of furnace shell (mm): 5200

Furnace shell height (mm): 3300

Furnace shell inner diameter (mm): 4050

Hearth depth (mm): 1720

Electrode diameter (mm): 750

Electrode material: standard electrode paste self-baking

Electrode pole center circle diameter (mm): 1930

Furnace lining material: high-alumina brick and carbon brick

Petroleum coke ash content: 0.10-1.44% and 0.35% sulfur

Petroleum coke particle size (mm): 0-10mm, mostly 0-5mm

The silicon steel scrap comprises the following impurities in percentage by weight: mn is less than 0.34, Cr is less than 0.04,

P＜0.026，S＜0.025

the quartz stone uses the quartz stone with the requirements

Quartz stone, petroleum coke and silicon steel filings (100: 46: 12-14)

The components of the high-purity silicon iron obtained by smelting are shown in the table 2,

TABLE 2 high-purity Si Fe composition

The ST-2 silicon iron is used for producing high-grade non-oriented silicon steel by Wu Steel. ST-4 is used for smelting oriented silicon steel, and the silicon steel yield is 100%. The method is used for producing the ferrosilicon, and under the condition that the electric power is normal, the power consumption is 7800-8500 DEG per ton of ferrosilicon.

Error meter

After preceding error reconnaissance of file name page line reconnaissance

Specification 2 Table 1 AL < 0.1 AL < 0.5

AL AL

4 table 20.5

0.10 0.10

0.1

Claims (4)

1. A method for smelting high-purity ferrosilicon using a submerged arc furnace, characterized in that selected quartz stone, petroleum coke (or petroleum coke plus a small amount of other carbon), and silicon steel chips are used as raw materials, and the petroleum coke particle size is 0-10mm, and the optimal particle size is 0-5mm. 2. The method according to claim 1, wherein the raw material ratio is quartz stone: petroleum coke: silicon steel chips (weight) = 100: 40-55: 5-55, with fixed carbon as the reference amount. 3. The method according to claim 1, wherein the chemical weight composition of the selected quartz stone is _SiO2 >98.0%, _Al2O3 < _0.03 %, CaO<0.01%, and the total amount of other impurities except iron oxide is less than 0.02%. 4. In the various grades of high-purity ferrosilicon produced by this method, Si and Fe are effective elements, and the impurity content can be controlled in the range of C0.05-0.003%, S0.01-0.002%, P＜0.02%, V0.05-0.001%, B0.01-0.002%, Mn＜0.10%, Mg0.05-0.005%, Ti0.05-0.007%, Ca0.05-0.002%, Ca＜0.05%, Cr＜0.05%, Ni＜0.05%, Zr0.01-0.003%, Al＜0.1%, and the total amount of other impurities is less than 0.05%.

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