CN107779613B

CN107779613B - Method for smelting metal chromium with low aluminum content

Info

Publication number: CN107779613B
Application number: CN201711037205.7A
Authority: CN
Inventors: 王景军; 王明秋
Original assignee: 王景军
Current assignee: JINZHOU METAL MATERIAL Research Institute
Priority date: 2017-10-30
Filing date: 2017-10-30
Publication date: 2020-02-14
Anticipated expiration: 2037-10-30
Also published as: CN107779613A

Abstract

A method for smelting metallic chromium with low aluminum content comprises the following steps: mixing industrial chromic oxide, calcium oxide, aluminum oxide or magnesium oxide and sodium oxide according to the mass ratio of 1-5:0.01-0.1:6-9:0.01-0.4 by using a mixer to obtain a mixture A; mixing industrial chromic oxide and carbon according to the mass ratio of 1:0.1-0.5 by using a mixer to obtain a mixture B; adding the mixture A into an electric furnace to be completely melted, adding the mixture B, and melting the materials added later completely at the temperature of more than 1750 ℃ in the electric furnace; naturally cooling to a temperature lower than 100 ℃, discharging, removing slag on the surface to obtain a metal chromium block, crushing and packaging to obtain commercial metal chromium. The method has the advantages of low energy consumption and high product purity.

Description

Method for smelting metal chromium with low aluminum content

Technical Field

The invention relates to the field of chromium metal smelting, in particular to a method for smelting chromium metal with low aluminum content.

Background

Chromium metal is commonly used in the smelting of superalloys, resistance alloys, precision alloys and other non-ferrous based alloys. With the progress of science and technology at home and abroad, the effect of high-quality metal chromium is greater and greater. The production method of metal chromium includes electro-silicothermic process, aluminothermic process and electrolytic process, etc., and the electro-silicothermic process is eliminated because the silicon content in the alloy is greater than 2%. With the increasing importance of pure chromium in the late 60 s, the efforts for preparing metallic chromium by electrolysis have been greatly increased. The aluminothermic process uses chromium sesquioxide as raw material and aluminium powder as reducing agent to produce chromium metal. Because the production process is simple, the equipment investment is saved, the occupied area is small and the alloy quality is high, the method is a widely adopted production method, and at present, the metal chromium is produced only by using an aluminothermic method in China. The typical aluminothermic method is mostly adopted abroad, and the recovery rate of the chromium is 83-85 percent.

The conventional aluminothermic method for smelting chromium generally uses aluminum particles as a reducing agent and a heating agent, so that chromium oxide reacts violently in a short time to emit large amount of heat and smelt metallic chromium, aluminum is used as the heating agent and the reducing agent, the aluminothermic method has great defects, ① has high aluminum content in products due to aluminothermic reduction, ② chromium metal recovery rate is low, ③ metallic aluminum in the aluminothermic reduction comes from electrolysis of metallurgical aluminum oxide produced in chemical industry, sewage and red mud are generated in the chemical industry, each ton of metallic chromium generates 0.645 ton of aluminum production pollution, and energy consumption is high.

The vacuum carbon reduction method uses chromic oxide and carbon powder to make into block mass, and then the block mass is placed in a vacuum furnace, and decarburized at the temperature lower than the melting point of metal so as to produce micro-carbon or ultra-micro-carbon metal chromium.

The electrolytic process is to prepare chromic anhydride or chromium ammonium alum by chemical treatment with ferrochrome as raw material. In the chromic anhydride electrolysis method, the chromic concentrate is roasted, leached and acidified to obtain chromic anhydride, and the chromic anhydride is electrolyzed in an aqueous solution to finally obtain metal chromium. The ammoniochrome electrolysis process can be used to produce ferrochromium, chromium concentrate or chrome-magnesia. When the chromium concentrate is prepared, the chromium concentrate can be directly obtained by acidolysis from the chromium concentrate. The method has long treatment process, high equipment pressure required by acidolysis and large investment.

Disclosure of Invention

The invention aims to solve the technical problems of reducing the aluminum content in the metal chromium product and improving the yield of chromium. The invention designs a purification slag, so that impurities in the smelted chromium metal are purified to obtain the chromium metal without aluminum; specifically, calcium oxide, chromium oxide, aluminum oxide or magnesium oxide is used as a slag system, the melting temperature is controlled to be above 1750 ℃, and meanwhile, the process steps are adjusted, so that the yield of chromium is further improved.

A method for smelting metallic chromium with low aluminum content comprises the following steps: mixing industrial chromic oxide, calcium oxide, aluminum oxide or magnesium oxide and sodium oxide according to the mass ratio of 1-5:0.01-0.1:6-9:0.01-0.4 by using a mixer to obtain a mixture A; mixing industrial chromic oxide and carbon according to the mass ratio of 1:0.1-0.5 by using a mixer to obtain a mixture B; adding the mixture A into an electric furnace to be completely melted, adding the mixture B, and melting the materials added later completely at the temperature of more than 1750 ℃ in the electric furnace; naturally cooling to a temperature lower than 100 ℃, discharging, removing slag on the surface to obtain a metal chromium block, crushing and packaging to obtain commercial metal chromium.

The content of chromium sesquioxide in the industrial chromium sesquioxide is higher than 95 wt%, preferably higher than 99 wt%, and the particle size is 1-50 mm, preferably less than 5-20 mm.

The carbon may be coke or charcoal, and has an average particle size of 1 to 50 mm, preferably 5 to 20 mm; the sulphur content is less than 0.1 wt.%, preferably less than 0.01 wt.%.

Preferably, the industrial chromium oxide, the calcium oxide, the aluminum oxide or the magnesium oxide and the sodium oxide are mixed in the mixture A according to the mass ratio of 1-4:0.04-0.05:7.5-8: 0.05-0.1.

Preferably, the industrial chromium sesquioxide and the carbon in the mixture B are mixed according to the mass ratio of 1: 0.1-0.5.

The method of the invention mainly comprises the following reactions in the blast furnace:

14Cr₂O₃+54C＝4Cr₇C₃+2CO

Cr₂O₃+3C＝2Cr+3CO

SiO₂+2C＝Si+2CO

Fe₂O₃+3C＝2Fe+3CO

the product of the reaction, namely carbon monoxide, overflows upwards and is combusted to release heat and generate carbon dioxide to be released;

the reduction products such as chromium carbide, silicon and the like are settled and enter a pre-melted slag layer to react with chromium oxide in the slag layer to generate chromium and carbon monoxide, the carbon monoxide overflows from the slag layer, and calcium silicate is remained in the slag layer, so that impurities are easily removed to obtain relatively pure metal chromium;

the method has the advantages that:

1. the recovery rate of chromium metal is improved by more than 5 percent;

2. the metal aluminum in the aluminothermic reduction is derived from the electrolysis of metallurgical aluminum oxide in chemical production, sewage and red mud can be generated in the chemical process, the consumption of 0.645 ton of aluminum is reduced by using electrothermal carbon to reduce each ton of metal chromium, and meanwhile, the pollution generated by 0.645 ton of aluminum production is reduced;

3. the chlorine gas emission generated by potassium chlorate reaction in each ton of metal chromium is reduced by 0.046 ton of metal chromium; energy conservation and consumption reduction, wherein the comprehensive energy consumption of each ton of metal chromium is reduced by 1.589 tons of standard coal;

4. the aluminum content in the metal chromium of the product is reduced;

Detailed Description

The technical solution of the present invention is not limited to the following specific embodiments, but includes any combination between the specific embodiments.

Example 1

1. Mixing 12kg of chromium oxide for metallurgy, 0.5kg of calcium oxide, 80kg of aluminum oxide and 3kg of sodium oxide for 15 minutes by using a mixer; obtaining a mixture 1;

2. mixing 100kg of chromium oxide with purity of more than 99.0% and average particle size of 1-40 mm and 23kg of carbon with sulfur content of less than 0.01% and average particle size of 5-30 mm by a mixer for 10 minutes to obtain a mixture 2;

3. adding the mixture 1 into an electric furnace, completely melting by using high voltage, adding the mixture 2, and melting the materials added in the electric furnace at a temperature of more than 1750 ℃ to completely clear the materials;

4. naturally cooling to a temperature lower than 100 ℃, discharging, removing slag on the surface to obtain a metal chromium block, crushing and packaging to obtain commercial metal chromium.

Example 2

1. Mixing 18kg of chromium oxide for metallurgy, 0.45kg of calcium oxide, 78.5kg of magnesium oxide and 2kg of sodium oxide for 15 minutes by using a mixer; obtaining a mixture 1;

2. mixing 100kg of chromium oxide with purity of more than 99.0% and average particle size of 5-40 mm and 23kg of carbon with sulfur content of less than 0.01% and average particle size of 5-30 mm by a mixer for 10 minutes to obtain a mixture 2;

3. adding the mixture 1 into an electric furnace, completely melting by using high voltage, gradually adding the mixture 2, and melting the materials completely at the temperature of more than 1750 ℃ in the electric furnace;

Example 3

1. 10kg of chromium sesquioxide for metallurgy, 0.4kg of calcium oxide, 85kg of aluminum oxide and 4kg of magnesium oxide are mixed for 15 minutes by a mixer; obtaining a mixture 1;

2. mixing 100kg of chromium oxide with purity of more than 99.0% and average particle size of 20-40 mm and 23kg of carbon with sulfur content of less than 0.01% and average particle size of 5-30 mm by a mixer for 10 minutes to obtain a mixture 2;

Example 4

1. 30kg of chromium oxide for metallurgy, 0.4kg of calcium oxide, 85kg of aluminum oxide, 2kg of magnesium oxide and 2kg of sodium oxide are mixed for 15 minutes by a mixer; obtaining a mixture 1;

2. 100kg of chromium oxide with the purity of more than 99.0 percent and the average grain size of 10-40 mm and 23kg of carbon with the sulfur content of less than 0.01 percent and the average grain size of 5-30 mm are mixed by a mixer for 10 minutes to obtain a mixture 2;

The chromium produced in examples 1 to 4 was subjected to compositional examination, and the results are shown in Table 1.

TABLE 1

Numbering	Cr％	Fe％	Si％	Al％	Cu％	C％
							1	98.5	0.4	0.3	0.02	0.04	0.7
2	98.0	0.35	0.4	0.03	0.06	0.8
							3	98.8	0.32	0.3	0.02	0.03	0.7
4	98.6	0.35	0.35	0.03	0.04	0.7

Compared with the traditional method, the method of the invention has the following comparison of raw material and energy consumption for producing each ton of metal chromium as shown in the table 2:

TABLE 2

	Chromium oxide	Electric power	Standard coal
				Aluminothermic process	1.713	90kwh	2.589
The invention relates to an electric heating carbon method	1.630	4500kwh	1.0

As can be seen from the table, the chromium production method of the invention can greatly reduce the energy consumption, reduce the production cost, improve the yield of chromium and achieve unexpected technical effects.

Claims

1. A method for smelting metallic chromium with low aluminum content comprises the following steps: mixing industrial chromic oxide, calcium oxide, aluminum oxide or magnesium oxide and sodium oxide according to the mass ratio of 1-5:0.01-0.1:6-9:0.01-0.4 by using a mixer to obtain a mixture A; mixing industrial chromic oxide and carbon according to the mass ratio of 1:0.1-0.5 by using a mixer to obtain a mixture B; adding the mixture A into an electric furnace to be completely melted, adding the mixture B, and melting the materials added later completely at the temperature of more than 1750 ℃ in the electric furnace; naturally cooling to a temperature lower than 100 ℃, discharging, removing slag on the surface to obtain a metal chromium block, crushing and packaging to obtain commercial metal chromium; the content of chromium sesquioxide in the industrial chromium sesquioxide is higher than 95 wt%, and the particle size is 1-50 mm; the carbon has a sulfur content of less than 0.1 wt%.

2. The method of claim 1, wherein said industrial chromium trioxide comprises greater than 99% by weight chromium trioxide; the grain diameter is 5-20 mm.

3. The method of claim 1, wherein the carbon has an average particle size of 5 to 20 mm; the sulphur content is less than 0.01 wt%.

4. The method as claimed in claim 1, wherein the industrial chromium oxide, calcium oxide, aluminum oxide or magnesium oxide and sodium oxide are mixed in a mass ratio of 1-4:0.04-0.05:7.5-8:0.05-0.1 in the mixture A.