Method for two-stage production of titanium slag

Abstract

FIELD: metallurgy.SUBSTANCE: invention relates to the production of titanium slags during smelting and reduction of titanium-containing raw materials. Preparation of charge materials, mixing them, obtaining ilmenite-coal briquettes, their heat treatment in a ring furnace at a temperature of 1500-1700°C, unloading and cooling with separation of metal and slag are carried out. At the first stage, heat treatment of the briquettes is carried out for 20-40 minutes, and after heat treatment, the metallised briquettes are cooled with water at a rate of 10-30°C / s. At the second stage, the briquettes are crushed and separated by pneumatic separation by size into two products: -0.056 mm – titanium slag and +0.056 mm – slag-metal product, which is sieved by size into fractions -3.0+0.056 mm – return and +3.0 mm – metal.EFFECT: obtaining titanium slag with low iron content.4 cl, 1 tbl, 1 ex

Description

[0001] The invention relates to metallurgy, namely to the production of titanium slags during the smelting and reduction of titanium-containing raw materials.

[0002] A known method for producing titanium slags in an ore-thermal furnace (RU Patent No. 2492262, filed April 20, 2012, published September 10, 2013, IPC C22C 33 / 00), includes drying and heating the furnace, preparing a charge of titanium-containing concentrate and a reducing agent, loading it and melting it using electrodes to obtain a melt, building up a skull on the inner wall of the furnace lining with a portioned supply of a reducing agent, reducing melting, further reduction of the melt with a reducing agent, settling and periodic tapping of the melt to obtain titanium slag and ferrous material, characterized in that before heating the furnace, heated titanium slag is sequentially loaded into it, then metal waste and a charge consisting of from a reducing agent and titanium-containing concentrate with a reducing agent:concentrate ratio of 1:(11-16), they are distributed evenly on the furnace bottom,The furnace is then heated and metal waste is loaded between the electrodes to form an arc. A mixture consisting of titanium-containing concentrate, reducing agent, and metal waste is added in small portions to form a melt under the electrodes, with a concentrate:reducing agent:metal waste ratio of 1:(0.04-0.15):(0.3-0.6). The method for producing titanium slag in an ore-smelting furnace allows for a significant increase in the service life of the furnace by selecting specific components for preparing the furnace for smelting and adjusting their quantitative ratios.

[0003] The disadvantage of this method is the high heat and energy costs in obtaining titanium slag and the low productivity of the ore-smelting furnace.

[0004] A two-stage method for producing titanium slags is known (Garmata V.A., Petrunko A.N., Galitsky N.V., Olesov Yu.G., Sandler R.A. Titan. - M.: Metallurgy, 1983, pp. 215-219), which includes, in the first stage, the reduction of ilmenite concentrate in the form of pellets at a temperature of 1050-1100 °C in a rotary kiln and smelting of reduced pellets in an ore-smelting furnace at a temperature of 1700-1800 °C and periodic tapping of the melt with separation of titanium slag and metal semi-finished product. Before further processing, titanium slag is crushed to a size of less than 100 µm. The two-stage technology makes it possible to reduce the cost of titanium slag production by reducing energy consumption by 25%.

[0005] The disadvantage of this method is the high content of iron oxide in titanium slag.

[0006] The closest in technical essence and achieved result to the claimed invention is a method for processing titanium-iron materials and a device for its implementation (RU Patent No. 2238989, declared on 10.02.2003, published on 27.10.2004, IPC C22B 1 / 243, C22B 34 / 12), including mixing crushed titanium-iron and carbon-containing materials, loading into a furnace, heating and heat treatment with flue gases, unloading and cooling with separation of metal and slag, removal of exhaust flue gases, characterized in that at the mixing stage, liquid glass is fed in an amount of 3-5 wt. % of the mixture weight are produced into briquettes under pressure, which are preheated and then fed for heating and heat treatment, with the preheating being carried out by the exhaust flue gases obtained at the heating and heat treatment stage.Furthermore, the briquettes are preheated at 800-1000°C, heat treated at 1500-1700°C, produced in 5-10 cm3 volumes, and pressure maintained at 40-60 MPa during briquette production. The method and equipment used for processing titanium-iron materials significantly reduce fuel consumption and increase iron recovery from titanium-iron-containing raw materials.

[0007] The disadvantage of the prototype method is the high iron content in the titanium slag.

[0008] The objective of the claimed method is to create a method for producing titanium slag with a low iron content.

[0009] The stated problem is solved in that in the known method of two-stage production of titanium slag, including the preparation of charge materials, their mixing, production of ilmenite-coal briquettes, their heat treatment in an annular furnace at a temperature of 1500-1700 °C, unloading and cooling with separation of metal and slag, according to the invention, at the first stage, the heat treatment of the briquettes is carried out for 20-40 minutes, and after the heat treatment, the metallized briquettes are cooled with water at a rate of 10-30 °C / s, at the second stage, the briquettes are crushed and separated by pneumatic separation by size into two products: -0.056 mm - titanium slag and +0.056 mm - slag-metal product, which is sifted by size into fractions of -3.0 +0.056 mm - return and +3.0 mm - metal.

[0010] In addition, at the mixing stage, the return of the fraction -3.0+0.056 mm is additionally introduced into the batch in an amount of 10-30 wt.% of the batch weight.

[0011] In addition, at the mixing stage, fluorite is additionally introduced into the batch in an amount of 2-4 wt.% of the batch weight.

[0012] In addition, at the mixing stage, sodium chloride is additionally added to the batch in an amount of 6-12 wt.% of the batch weight.

[0013] The proposed method for the two-stage production of titanium slag differs from the prototype in that at the first stage, heat treatment is carried out for 20-40 minutes, the briquettes are cooled with water at a rate of 10-30 °C / s, at the second stage, the briquettes are crushed and separated by pneumatic separation by size into two products: -0.056 mm - titanium slag and +0.056 mm - slag-metal product, which is sieved by size into fractions of -3.0+0.056 mm - return and +3.0 mm - metal.

[0014] The heat treatment time of briquettes in a ring furnace depends on the rate of carbothermic reduction of iron oxides and coagulation of metallic iron in the titanium slag mass, as well as the briquette weight. The lower limit of the heat treatment time, 20 minutes, is determined by the minimum time required to reduce the iron and coagulate it into granules no smaller than 50 μm for briquette weights less than 50 g. The upper limit of the heat treatment time, 40 minutes, is determined by the maximum time required to reduce the iron and coagulate it into granules no smaller than 50 μm for briquette weights over 50 g.

[0015] The limits of the cooling rate of metallized briquettes with water are determined by the oxidation process of metallic iron. The lower limit of the cooling rate, i.e., 10°C / s, depends on the degree of iron oxidation by water. At a cooling rate of less than 10°C / s, the degree of metallic iron oxidation by water exceeds 5%, resulting in an increase in the iron content of the titanium slag of over 8%. The upper limit of the cooling rate, i.e., 30°C / s, is determined by the capabilities of existing equipment for cooling briquettes in water. Cooling rates above 30°C / s cannot be achieved with existing equipment.

[0016] The use of pneumatic separation allows the separation of crushed metallized briquettes by size into two products: -0.056 mm - titanium slag and +0.056 mm - slag-metal product, which is further sized into fractions of -3.0 +0.056 mm - return and +3.0 mm - metal. The pneumatic separation size of 0.056 mm is determined by the degree of coagulation of metallic iron in the titanium slag during heat treatment. With a pneumatic separation size of more than 0.056 mm, some metallic iron passes into titanium slag. With a pneumatic separation size of less than 0.056 mm, the yield of titanium slag decreases.

[0017] Additional screening of slag metal products larger than 0.056 mm allows for the most complete recovery of iron larger than 3.0 mm in the metal product. The screened product of +0.056-3.0 mm is titanium slag with an increased iron content and is returned to the charge for briquetting.

[0018] The amount of recycled material in the batch for briquette production (10-30 wt.%) is determined by the product yield of +0.056-3.0 mm during sieving of the slag-metal mixture. The minimum yield of +0.056-3.0 mm is 10%. The upper limit of the amount of +0.056-3.0 mm in the batch is determined by the strength of the briquettes. With a product content of +0.056-3.0 mm in the batch, the strength of the briquettes decreases.

[0019] The fluorite content of 2-4% by weight in the batch for briquette production is determined by the iron coagulation process. When the fluorite content in the batch is less than 2%, the iron coagulation process is inhibited, and a large number of iron particles smaller than 0.056 mm in size are converted into titanium slag. When the fluorite content in the batch is greater than 4%, the calcium oxide and fluorine content in the titanium slag increases, exceeding the permissible limit.

[0020] The sodium chloride content of 6-12% by weight in the batch for briquette production is determined by the iron coagulation process. At a sodium chloride content of less than 6% in the batch, iron coagulation is inhibited, and a large number of iron particles smaller than 0.056 mm in size are converted into titanium slag. At a sodium chloride content of more than 12% in the batch, the sodium chloride content in the titanium slag increases, exceeding the permissible limit.

[0021] Example of the method implementation. The proposed invention was tested in laboratory conditions by simulating the conditions of heat treatment of ilmenite-coal briquettes in a ring furnace. Chemical composition of ilmenite concentrate, %: Fe 25.17; TiO256.9; SiO21.6; Al2O32.4; CaO 0.2; MgO 0.9; MnO 1.3; V2O50.24; Cr2O32.6; P2O50.36; S 0.05; ppb 0.15. Anthracite grade AC was used as a reducing agent. Molasses was used as a binder in the production of briquettes. Ilmenite-coal briquettes were obtained on a hydraulic press in press molds of different diameters. Briquettes weighing 40 and 80 grams were produced. Heat treatment in a ring furnace was simulated by firing the briquettes in a carbon resistance furnace. After firing, the briquettes were cooled with water at varying rates by varying their residence time in the water. After cooling, the metallized briquettes were ground in a mill, and the slag was separated from the metal in a laboratory magnetic separator and pneumatic separator.The +0.056 mm fraction was sieved on a 3.0 mm sieve. The +0.056-3.0 mm undersize product was returned to the charge, while the oversize product was metallic iron. Pneumatic separation yielded titanium slag containing 85.0-88.6% TiO2, 1.2-6.2% Fe, 3.0-4.0% SiO2, and 2.0-3.0% Al2O3, which meets the requirements of the TiCL14 production technology.

[0022] The experimental data results from modeling the two-stage titanium slag production method are presented in the table. It follows from the data provided that the use of the proposed two-stage titanium slag production method, compared to the known prototype method [3], ensures a reduction in the iron content in the titanium slag from 16.8 to 1.2-6.2%.

[0023] The claimed method for producing titanium slag can be implemented in industrial conditions using known raw materials and metallurgical equipment.

[0024] Sources of information:

[0025] 1. Patent RF 2492262, application. 20.04.2012, publ. 9 / 10 / 2013, C22C 33 / 00;

[0026] 2. Garmata V., Petrunko A.N., Galitsky N.V., Olesov Yu.G., Sandler R.A. Titan.-M.: Metallurgy, 1983, p. 215-219;

[0027] 3. Patent RF 2238989, application. 10.02.2003, published. 10 / 27 / 2004, C22B 1 / 243, 34 / 12.

[0028]

Claims

1. A two-stage method for producing titanium slag, including preparing charge materials, mixing them, producing ilmenite-coal briquettes, heat treating them in a ring furnace at a temperature of 1500-1700 °C, unloading and cooling with separation of metal and slag, characterized in that at the first stage the heat treatment of the briquettes is carried out for 20-40 minutes, and after the heat treatment the metallized briquettes are cooled with water at a rate of 10-30 °C / s, at the second stage the briquettes are crushed and separated by pneumatic separation by size into two products: -0.056 mm - titanium slag and +0.056 mm - slag-metal product, which is sieved by size into fractions of -3.0+0.056 mm - return and +3.0 mm - metal.

2. The method according to paragraph 1, characterized in that at the mixing stage, a return of the -3.0+0.056 mm fraction is additionally introduced into the batch in an amount of 10-30% of the batch weight.

3. The method according to paragraph 1, characterized in that at the mixing stage, fluorite is additionally introduced into the batch in an amount of 2-4% of the batch weight.

4. The method according to paragraph 1, characterized in that at the mixing stage, sodium chloride is additionally introduced into the batch in an amount of 6-12% of the batch weight.

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