CN107779613B - Method for smelting metal chromium with low aluminum content - Google Patents

Abstract

A metal chromium smelting method with low aluminum content, comprising the following steps: mixing industrial chromium 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 Mix with a mixer to obtain mixture A; mix industrial chromium trioxide and carbon according to a mass ratio of 1:0.1-0.5 with a mixer to obtain mixture B; add mixture A into the electric furnace and melt it completely, Add the mixture B, and the smelting temperature of the electric furnace is greater than 1750 ℃ to make all the added materials clear; naturally cool down and cool down to a temperature lower than 100 ℃, and then release the furnace, remove the slag on the surface to obtain a metal chromium block, which is crushed and packaged to obtain a commercial metal chromium . The method has the advantages of low energy consumption and high product purity.

Description

A kind of metal chromium smelting method with low aluminum content

technical field

The invention relates to the field of chromium metal smelting, in particular to a low aluminum-containing chromium metal smelting method.

Background technique

Metal chromium is usually used for smelting superalloys, resistance alloys, precision alloys and other non-ferrous alloys. With the advancement of science and technology at home and abroad, the role of high-quality metal chromium is increasing. The production methods of metallic chromium include electrosilicothermic method, aluminothermic method, electrolysis method, etc. The electrosilicic heating method has long been eliminated because the silicon content in the alloy is more than 2%. In the late 1960s, as the importance of pure chromium continued to increase, efforts to electrolytically produce metallic chromium were greatly enhanced. The aluminothermic method uses chromium trioxide as a raw material and aluminum powder as a reducing agent to produce metallic chromium. Due to its simple production process, low equipment investment, small footprint and high alloy quality, it has always been a widely adopted production method. At present, my country only uses the aluminothermic method to produce metallic chromium. Most foreign countries adopt the typical aluminothermic method, and the recovery rate of chromium is 83%-85%.

Common aluminothermic smelting of chromium usually uses aluminum particles as reducing agent and exothermic agent, so that chromium oxides react violently in a short time, release a lot of heat, and smelt metal chromium; aluminum is used here as exothermic agent and reducing agent. . The aluminothermic method has great drawbacks: ①The aluminum content in the product is high due to the aluminothermic reduction; ②The recovery rate of chromium metal is low; ③The metal aluminum in the aluminothermic reduction comes from the metallurgical aluminum oxide produced by the chemical industry Sewage and red mud will be produced in the chemical process; 0.645 tons of aluminum pollution will be produced per ton of metal chromium; high energy consumption.

The vacuum carbon reduction method uses chromium trioxide and carbon powder to make agglomerates, put them into a vacuum furnace, and decarburize them at a temperature lower than the melting point of the metal to produce micro-carbon or ultra-micro carbon metal chromium.

The electrolysis method uses ferrochromium as raw material, and chemical treatment method is used to prepare chromic anhydride or chromoammonium alum as the raw material for electrolytic production of chromium. In the chromic anhydride electrolysis method, the chromium concentrate is roasted-leached-acidified, and then chromic anhydride is obtained, and the chromic anhydride is electrolyzed in an aqueous solution to finally obtain metallic chromium. Chromium ammonium alum electrolysis can be prepared from ferrochromium alloys, chromium concentrates or chromium magnesium ore. When it is produced from chromium concentrate, it can be directly obtained by acid hydrolysis from chromium concentrate. The treatment process of this method is long, the equipment pressure required for acid hydrolysis is high, and the investment is large.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to reduce the aluminum content in the metallic chromium product, and at the same time improve the yield of chromium. The invention designs a purification slag, so that the impurities in the metal chromium after smelting are purified, and the metal chromium without aluminum is obtained; The melting temperature is controlled above 1750°C, and the process steps are adjusted at the same time to further improve the yield of chromium.

A metal chromium smelting method with low aluminum content, comprising the following steps: mixing industrial chromium 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 Mix with a mixer to obtain mixture A; mix industrial chromium trioxide and carbon according to the mass ratio of 1:0.1-0.5 with a mixer to obtain mixture B; add mixture A into the electric furnace and melt it completely, Add the mixture B, and the smelting temperature of the electric furnace is greater than 1750 ℃ to make all the added materials clear; naturally cool down and cool down to a temperature lower than 100 ℃, and then release the furnace, remove the slag on the surface to obtain a metal chromium block, which is crushed and packaged to obtain a commercial metal chromium .

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

The carbon can be coke or charcoal, the average particle size is 1-50 mm, preferably 5-20 mm; the sulfur content is less than 0.1 wt%, preferably less than 0.01 wt%.

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

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

The method of the present invention mainly takes place following reaction in blast furnace:

14Cr ₂ O ₃ +54C=4Cr ₇ C ₃ +2CO

Cr ₂ O ₃ +3C=2Cr+3CO

SiO ₂ +2C=Si+2CO

Fe ₂ O ₃ +3C=2Fe+3CO

The reaction product carbon monoxide overflows upwards and burns to release heat and generates carbon dioxide to release;

The reduction products, such as chromium carbide and silicon, settle into the pre-melted slag layer and react with the chromium oxide in the slag layer to generate chromium and carbon monoxide. Obtain relatively pure metallic chromium;

Advantages of the method of the present invention:

1. The recovery rate of chromium metal is increased by more than 5%;

2. The metal aluminum in the aluminothermic reduction comes from the electrolysis of metallurgical aluminum oxide produced by the chemical industry. Sewage and red mud will be generated in the chemical process. The electrothermal carbon reduction reduces the consumption of aluminum by 0.645 tons per ton of metal chromium, and at the same time reduces the consumption of aluminum. 0.645 tons of pollution from aluminum production;

3. Each ton of chromium metal reduces the chlorine gas emission produced by the reaction of potassium chlorate in the aluminothermic method by 0.046 tons; saves energy and reduces consumption, and reduces the comprehensive energy consumption per ton of chromium metal by 1.589 tons of standard coal;

4. Reduce the aluminum content in the product metal chromium;

Detailed ways

The technical solutions of the present invention are not limited to the specific embodiments listed below, but also include any combination of specific embodiments.

Example 1

1. Mix 12kg of chromium trioxide for metallurgy, 0.5kg of calcium oxide, 80kg of aluminum oxide, and 3kg of sodium oxide with a mixer for 15 minutes; get mixture 1;

2. Mix 100kg of chromium trioxide with a purity of >99.0% and an average particle size of 1-40 mm and 23kg of carbon with a sulfur content of <0.01% and an average particle size of 5-30 mm, and mix them with a mixer for 10 minutes to obtain a mixture. material 2;

3. Add the mixture 1 into the electric furnace and melt it completely with high voltage, then add the mixture 2, and the smelting temperature of the electric furnace is higher than 1750 ℃, so that all the materials added later are dissolved;

4. Naturally cool down and cool down to a temperature lower than 100 ℃ and then release the furnace, remove the slag on the surface to obtain metal chrome blocks, crush and package to obtain commercial metal chrome.

Example 2

1. 18kg of metallurgical chromium oxide, 0.45kg of calcium oxide, 78.5kg of magnesium oxide, 2kg of sodium oxide were mixed for 15 minutes with a mixer; Mixture 1 was obtained;

2. Mix 100kg of chromium trioxide with a purity of >99.0% and an average particle size of 5-40 mm and 23kg of carbon with a sulfur content of <0.01% and an average particle size of 5-30 mm, and mix with a mixer for 10 minutes to obtain a mixed solution. material 2;

3. Add the mixture 1 into the electric furnace and melt it completely with high voltage, then gradually add the mixture 2, and the smelting temperature of the electric furnace is greater than 1750 ℃, so that all the materials added later are cleared;

4. Naturally cool down and cool down to a temperature lower than 100 ℃ and then release the furnace, remove the slag on the surface to obtain metal chrome blocks, crush and package to obtain commercial metal chrome.

Example 3

1. Mix 10kg of metallurgical chromium oxide, 0.4kg of calcium oxide, 85kg of aluminum oxide, and 4kg of magnesium oxide with a mixer for 15 minutes; get mixture 1;

2. Mix 100kg of chromium trioxide with a purity of >99.0% and an average particle size of 20-40 mm and 23kg of carbon with a sulfur content of <0.01% and an average particle size of 5-30 mm with a mixer for 10 minutes to obtain a mixture. material 2;

3. Add the mixture 1 into the electric furnace and melt it completely with high voltage, then add the mixture 2, and the smelting temperature of the electric furnace is higher than 1750 ℃, so that all the materials added later are dissolved;

4. Naturally cool down and cool down to a temperature lower than 100 ℃ and then release the furnace, remove the slag on the surface to obtain metal chrome blocks, crush and package to obtain commercial metal chrome.

Example 4

1. Metallurgical 30kg of chromium oxide, 0.4kg of calcium oxide, 85kg of aluminum oxide, 2kg of magnesium oxide, and 2kg of sodium oxide were mixed for 15 minutes with a mixer; Mixture 1 was obtained;

2. Mix 100kg of chromium trioxide with a purity > 99.0% and an average particle size of 10-40 mm and 23 kg of carbon with a sulfur content < 0.01% and an average particle size of 5-30 mm with a mixer for 10 minutes. material 2;

3. Add the mixture 1 into the electric furnace and melt it completely with high voltage, then add the mixture 2, and the smelting temperature of the electric furnace is higher than 1750 ℃, so that all the materials added later are dissolved;

4. Naturally cool down and cool down to a temperature lower than 100 ℃ and then release the furnace, remove the slag on the surface to obtain metal chrome blocks, crush and package to obtain commercial metal chrome.

Component detection was carried out on the chromium produced in Examples 1-4, and the results are shown in Table 1.

Table 1

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

The method of the present invention is compared with the traditional method, and the raw material and energy consumption of producing every ton of metallic chromium are compared as shown in table 2:

Table 2

Chromium trioxide electricity standard coal Aluminothermic method 1.713 90kwh 2.589 Electrothermal carbon method of the present invention 1.630 4500kwh 1.0

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

Claims (4)

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.