Method for recovering titanium from titanium-containing blast furnace slag

Abstract

The invention discloses a method for recovering titanium from titanium-containing blast furnace slag, and belongs to the technical field of industrial solid waste resource comprehensive utilization. The method for recovering the titanium from the titanium-containing blast furnace slag comprises the following steps that the molten titanium-containing blast furnace slag is subjected to water quenching, grinding and refining, and water-quenched slag is obtained; carrying out first acid leaching on the water-quenched slag by adopting nitric acid, and carrying out solid-liquid separation to obtain a leaching solution; carrying out titanium hydrolysis on the leachate, and carrying out solid-liquid separation to obtain hydrolyzed titanium slag; and washing the hydrolyzed titanium slag to remove impurities, and carrying out secondary acid leaching by adopting sulfuric acid to obtain a titanium-rich solution so as to realize titanium recovery. According to the method, the whole reaction system is mild, the production process is short, the production equipment investment and the production operation cost are reduced, the economic benefit of solid waste resource utilization is further improved, and the method has application and popularization value.

Description

Technical Field

[0001] This invention belongs to the field of comprehensive utilization technology of industrial solid waste resources, and specifically relates to a method for recovering titanium from titanium-containing blast furnace slag. Background Technology

[0002] Vanadium-titanium magnetite is often used in blast furnace ironmaking due to its difficulty in beneficiation. After blast furnace smelting, about 45% of the titanium in the vanadium-titanium magnetite enters the blast furnace slag. The amount of titanium-containing blast furnace slag is huge, and research on efficient comprehensive utilization is of great practical significance. However, TiO2 in titanium-containing blast furnace slag is difficult to be directly utilized due to the dispersed distribution of titanium and the small particle size. The current treatment method is mostly slag dumping. However, the dumping of titanium-containing blast furnace slag has brought the surrounding environment's carrying capacity to the limit, mainly in the following aspects: (1) Water pollution: Under the long-term leaching effect of rainwater, the soluble harmful components in titanium-containing blast furnace slag seep down from the ground surface with the rainwater and flow into the surrounding rivers and nearby groundwater, causing water pollution, seriously affecting the drinking water safety of local residents and livestock, and posing a potential threat to human and animal health; (2) Atmospheric pollution: Some fine particles adsorbed on the surface of titanium-containing blast furnace slag particles are easily blown and diffused into the atmosphere by the wind. In the surrounding atmosphere, it not only pollutes the air, but also contaminates the surrounding buildings and vegetation. Fine particles enter the body of organisms through the respiratory system, which greatly threatens the health of the surrounding residents; (3) Pollutes the soil: The harmful components in titanium-containing blast furnace slag are transferred to the soil with rainwater and accumulate, which leads to the alkalization and hardening of the soil structure and soil quality near the slag pile, affecting the activity of microorganisms in the soil, thereby hindering the growth of plant roots and causing the ecosystem to become unbalanced; (4) Causes natural disasters: The large-scale dumping of titanium-containing blast furnace slag will occupy a large area of ​​land, leading to an increasingly acute contradiction between waste slag and land. Secondly, the blast furnace slag piled up into mountains is very easy to loosen when encountering extreme weather, which is a potential hidden danger for natural disasters such as landslides and mudslides.

[0003] In recent years, due to the overcapacity in the steel industry and the environmental pollution caused by related industrial waste, which has harmed the entire society and economy, my country has put forward newer and higher requirements for energy conservation and emission reduction in the steel industry. Although titanium-containing blast furnace slag is a type of steel smelting waste, it is rich in a large number of valuable components. If extracted and utilized, it can produce a variety of high-value chemical powders. Its resource utilization is in line with the relevant policies of the National Industrial Green Development Plan (2016-2020) and is an important issue of long-term concern both domestically and internationally.

[0004] Therefore, researching and developing methods for the resource utilization of valuable components in titanium-containing blast furnace slag has significant environmental and economic benefits. Summary of the Invention

[0005] The problem to be solved by the present invention is to provide a method for recovering titanium from titanium-containing blast furnace slag, so as to solve the problems of low titanium recovery rate, complex recovery process and high recovery cost in existing titanium-containing blast furnace slag.

[0006] The technical solution adopted to solve its technical problem is a method for recovering titanium from titanium-containing blast furnace slag, comprising the following steps: (1) The molten titanium-containing blast furnace slag is water-quenched and ground into finer particles to obtain water-quenched slag; (2) The water-quenched slag was subjected to a first acid leaching with nitric acid, and the solid and liquid were separated to obtain the leachate; (3) The leachate is subjected to titanium hydrolysis, and solid-liquid separation is performed to obtain hydrolyzed titanium slag; (4) The hydrolyzed titanium slag is washed to remove impurities and then subjected to a second acid leaching with sulfuric acid to obtain a titanium-rich solution, thereby realizing the recovery of titanium.

[0007] The beneficial effects of the above-mentioned technical solution of this invention are as follows: The method of this invention involves two acid leaching processes. First, the water-quenched slag undergoes a first acid leaching, during which most of the titanium, magnesium, aluminum, calcium, and silicon enter the leaching solution when nitric acid is used for leaching. Then, during titanium hydrolysis, titanium and silicon co-hydrolyze and precipitate, yielding hydrolyzed titanium slag and hydrolysate. The hydrolyzed titanium slag contains titanium and silicon, while the hydrolysate contains calcium, magnesium, and aluminum. After washing the hydrolyzed slag, a second acid leaching is performed using sulfuric acid. At this time, titanium enters the sulfuric acid solution to obtain a titanium-rich solution, achieving titanium recovery. The remaining silicon is converted into high-purity silica in the form of silicon dioxide, achieving titanium recovery. The titanium-rich solution obtained after the second acid leaching is a sulfuric acid-based titanium solution, which can be directly used as raw material for titanium dioxide production, which is beneficial for subsequent utilization and industrialization.

[0008] Preferably, the molten titanium-containing blast furnace slag in step (1) is molten titanium-containing blast furnace slag produced by smelting and / or titanium-containing blast furnace slag that has been cooled and then reheated to a molten state.

[0009] More preferably, the molten titanium-containing blast furnace slag in step (1) is the molten titanium-containing blast furnace slag produced by smelting.

[0010] Preferably, in step (1), the water quenching slag with a fineness of -0.074 mm accounts for 50 to 100% of the total weight of the water quenching slag after grinding and refining.

[0011] More preferably, in step (1), the water quenching slag with a fineness of -0.074 mm accounts for 70 to 100% of the total weight of the water quenching slag after grinding and refining.

[0012] More preferably, in step (1), the water quenching slag with a fineness of -0.074 mm accounts for 90 to 100% of the total weight of the water quenching slag after grinding and refining.

[0013] Preferably, in step (2), the volume concentration of nitric acid is 5-50%; the temperature of the first acid leaching is 10-40℃ and the time is 0.5-3h; the solid-liquid ratio of water-quenched slag to nitric acid is 1:2-8.

[0014] More preferably, in step (2), the volume concentration of nitric acid is 10-30%; the temperature of the first acid leaching is 20-30°C and the time is 1-3 hours; the solid-liquid ratio of water-quenched slag to nitric acid is 1:3-8.

[0015] More preferably, in step (2), the volume concentration of nitric acid is 15-30%; the temperature of the first acid leaching is 25-30°C and the time is 2-3 hours; the solid-liquid ratio of water-quenched slag to nitric acid is 1:4-8.

[0016] Preferably, the titanium hydrolysis temperature in step (3) is 60~100℃ and the time is 0.5~3h.

[0017] More preferably, in step (3), the titanium hydrolysis temperature is 80~100℃ and the time is 1~3h.

[0018] More preferably, in step (3), the titanium hydrolysis temperature is 85~100℃ and the time is 1.5~2.5h.

[0019] More preferably, the solid-liquid separation method in steps (2) and (3) is filtration or centrifugation.

[0020] Preferably, the washing liquid in step (4) is water, the washing temperature is 20~50℃, and the solid-liquid ratio of the hydrolyzed titanium slag to the washing liquid is 1:1~6.

[0021] More preferably, in step (4), the washing temperature is 20~40℃ and the solid-liquid ratio of the hydrolyzed titanium slag to the washing liquid is 1:3~6.

[0022] More preferably, in step (4), the washing temperature is 25~40℃, and the solid-liquid ratio of the hydrolyzed titanium slag to the washing liquid is 1:3~5.

[0023] Preferably, in step (4), the volume concentration of sulfuric acid is 10-70%; the second acid leaching temperature is 50-100℃ and the time is 0.5-3h; the solid-liquid ratio of hydrolyzed titanium slag to sulfuric acid is 1:2-8.

[0024] More preferably, in step (4), the volume concentration of sulfuric acid is 20-60%; the second acid leaching temperature is 70-100℃ and the time is 1-3h; the solid-liquid ratio of hydrolyzed titanium slag to sulfuric acid is 1:3-7.

[0025] Preferably, in step (4), the volume concentration of sulfuric acid is 30-50%; the second acid leaching temperature is 90-100℃ and the time is 1.5-2.5h; the solid-liquid ratio of hydrolyzed titanium slag to sulfuric acid is 1:3-5.

[0026] Preferably, after the second acid leaching in step (4), titanium-rich solution and silica are obtained.

[0027] The present invention has the following beneficial effects: This invention effectively recovers titanium from titanium-containing blast furnace slag and transforms it into valuable chemical products, achieving refined resource utilization of various components and generating high added value. At the same time, this invention also ensures a mild reaction system and a streamlined production process, which helps reduce investment in production equipment and operating costs, further improving the economic benefits of solid waste resource utilization. Attached Figure Description

[0028] Figure 1 This is a flowchart of the method for recovering titanium from titanium-containing blast furnace slag according to the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of this invention, and not all of them.

[0030] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0031] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0032] Example 1 A method for recovering titanium from titanium-containing blast furnace slag includes the following steps: (1) The molten titanium-containing blast furnace slag produced by smelting is water-quenched and ground to a fineness of -0.074 mm, and the water-quenched slag accounts for 85% of the total weight of the water-quenched slag. (2) The water-quenched slag was first acid-leached at 30°C for 2 hours using nitric acid with a volume concentration of 25% at 30°C. Solid-liquid separation was achieved by filtration to obtain leachate. The solid-liquid ratio of the water-quenched slag to nitric acid was 1:7. (3) The leachate was subjected to titanium hydrolysis at 90°C for 2 hours, and solid-liquid separation was achieved by filtration to obtain hydrolyzed titanium slag; (4) The hydrolyzed titanium slag is washed and impurities are removed with water at a temperature of 25°C. The solid-liquid ratio of the hydrolyzed titanium slag to water is 1:4. Then, sulfuric acid with a volume concentration of 40% is used for a second acid leaching at 90°C for 2 hours to obtain titanium-rich liquid and solid silica, thereby realizing the recovery of titanium. The solid-liquid ratio of the washed and impurity-removed hydrolyzed titanium slag to sulfuric acid is 1:4.

[0033] A flowchart of the method for recovering titanium from titanium-containing blast furnace slag is shown below. Figure 1 .

[0034] Example 2 A method for recovering titanium from titanium-containing blast furnace slag includes the following steps: (1) The molten titanium-containing blast furnace slag produced by smelting is water-quenched and ground to a fineness of -0.074 mm, and the water-quenched slag accounts for 90% of the total weight of the water-quenched slag. (2) The water-quenched slag was first acid-leached at 25°C for 2 hours using nitric acid with a volume concentration of 25%. Solid-liquid separation was achieved by filtration to obtain leachate. The solid-liquid ratio of the water-quenched slag to nitric acid was 1:6. (3) The leachate was subjected to titanium hydrolysis at 100°C for 1.5 hours, and solid-liquid separation was achieved by filtration to obtain hydrolyzed titanium slag; (4) The hydrolyzed titanium slag is washed and impurities are removed with water at a temperature of 30°C. The solid-liquid ratio of the hydrolyzed titanium slag to water is 1:4. Then, sulfuric acid with a volume concentration of 40% is used for a second acid leaching at 100°C for 2 hours to obtain titanium-rich liquid and solid silica, thereby realizing the recovery of titanium. The solid-liquid ratio of the washed and impurity-removed hydrolyzed titanium slag to sulfuric acid is 1:4.

[0035] Example 3 A method for recovering titanium from titanium-containing blast furnace slag includes the following steps: (1) The titanium-containing blast furnace slag that has been cooled is reheated to a molten state at 1300℃, water-quenched and ground to a fineness of -0.074mm. The water-quenched slag accounts for 85% of the total weight of the water-quenched slag. (2) The water-quenched slag was first acid-leached at 30°C for 2 hours using nitric acid with a volume concentration of 25% at 30°C. Solid-liquid separation was achieved by filtration to obtain leachate. The solid-liquid ratio of the water-quenched slag to nitric acid was 1:6. (3) The leachate was subjected to titanium hydrolysis at 90°C for 2 hours, and solid-liquid separation was achieved by filtration to obtain hydrolyzed titanium slag; (4) The hydrolyzed titanium slag is washed and impurities are removed with water at a temperature of 25°C. The solid-liquid ratio of the hydrolyzed titanium slag to water is 1:4. Then, sulfuric acid with a volume concentration of 40% is used for a second acid leaching at 90°C for 2 hours to obtain titanium-rich liquid and solid silica, thereby realizing the recovery of titanium. The solid-liquid ratio of the washed and impurity-removed hydrolyzed titanium slag to sulfuric acid is 1:4.

[0036] Example 4 A method for recovering titanium from titanium-containing blast furnace slag includes the following steps: (1) The molten titanium-containing blast furnace slag produced by smelting is water-quenched and ground to a fineness of -0.074 mm. The water-quenched slag accounts for 50% of the total weight of the water-quenched slag. (2) The water-quenched slag was first acid-leached at 20°C for 3 hours using nitric acid with a volume concentration of 10%. Solid-liquid separation was achieved by filtration to obtain leachate. The solid-liquid ratio of the water-quenched slag to nitric acid was 1:3. (3) The leachate was subjected to titanium hydrolysis at 80°C for 1 hour, and solid-liquid separation was achieved by filtration to obtain hydrolyzed titanium slag. (4) The hydrolyzed titanium slag is washed and impurities are removed with water at a temperature of 20°C. The solid-liquid ratio of the hydrolyzed titanium slag to water is 1:6. Then, sulfuric acid with a volume concentration of 20% is used for a second acid leaching at 70°C for 1 hour to obtain titanium-rich liquid and solid silica, thereby realizing the recovery of titanium. The solid-liquid ratio of the washed and impurity-removed hydrolyzed titanium slag to sulfuric acid is 1:3.

[0037] Example 5 A method for recovering titanium from titanium-containing blast furnace slag includes the following steps: (1) The molten titanium-containing blast furnace slag produced by smelting is water-quenched and ground to a fineness of -0.074 mm, and the water-quenched slag accounts for 70% of the total weight of the water-quenched slag. (2) The water-quenched slag was first acid-leached at 30°C for 1 hour using nitric acid with a volume concentration of 30%, and the solid-liquid separation was achieved by filtration to obtain the leachate; wherein the solid-liquid ratio of the water-quenched slag to nitric acid was 1:8. (3) The leachate was subjected to titanium hydrolysis at 60°C for 3 hours, and solid-liquid separation was achieved by filtration to obtain hydrolyzed titanium slag; (4) The hydrolyzed titanium slag is washed and impurities are removed with water at a temperature of 50°C. The solid-liquid ratio of the hydrolyzed titanium slag to water is 1:1. Then, a second acid leaching is carried out at 100°C for 3 hours with sulfuric acid of 60% volume concentration to obtain titanium-rich liquid and solid silica, thereby realizing the recovery of titanium. The solid-liquid ratio of the washed and impurity-removed hydrolyzed titanium slag to sulfuric acid is 1:7.

[0038] Experimental Example The molten titanium-containing blast furnace slag in Examples 1-3 was taken from Panzhihua, Sichuan. The chemical composition of the water-quenched slag before and after grinding is shown in Table 1 below.

[0039] Table 1 Chemical composition of water-quenched slag before and after grinding

[0040] The titanium content in the titanium-rich solutions obtained from the recovery of titanium in Examples 1-3 was determined using GB / T 14506.32-2019 "Chemical Analysis Methods for Silicate Rocks Part 32: Determination of the Amounts of 20 Components Including Alumina by Mixed Acid Decomposition-Inductively Coupled Plasma Atomic Emission Spectrometry". The results are shown in Table 2.

[0041] Table 2 Titanium content in titanium-rich solution

[0042] As shown in Table 2, the titanium-rich liquid obtained using the method of this invention has a high titanium content and can be used for further titanium product production. The method of this invention enables rapid and efficient titanium recovery from titanium-containing blast furnace slag.

[0043] The present invention has been described according to the above embodiments. It should be understood that the above embodiments do not limit the present invention in any way. All technical solutions obtained by equivalent substitution or equivalent transformation fall within the scope of the present invention.

Claims

1. A method for recovering titanium from titanium-containing blast furnace slag, characterized in that, Includes the following steps: (1) The molten titanium-containing blast furnace slag is water-quenched and ground into finer particles to obtain water-quenched slag; (2) The water-quenched slag was subjected to a first acid leaching with nitric acid, and the solid and liquid were separated to obtain the leachate; (3) The leachate is subjected to titanium hydrolysis, and solid-liquid separation is performed to obtain hydrolyzed titanium slag; (4) The hydrolyzed titanium slag is washed to remove impurities and then subjected to a second acid leaching with sulfuric acid to obtain a titanium-rich solution, thereby realizing the recovery of titanium.

2. The method for recovering titanium from titanium-containing blast furnace slag as described in claim 1, characterized in that, In step (1), the fineness of the water-quenched slag after grinding and refining is -0.074 mm, accounting for 50-100% of the total weight of the water-quenched slag.

3. The method for recovering titanium from titanium-containing blast furnace slag as described in claim 1, characterized in that, In step (2), the volume concentration of nitric acid is 5-50%; the temperature of the first acid leaching is 10-40℃ and the time is 0.5-3h; the solid-liquid ratio of the water-quenched slag to nitric acid is 1:2-8.

4. The method for recovering titanium from titanium-containing blast furnace slag as described in claim 1, characterized in that, In step (3), the titanium hydrolysis temperature is 60~100℃ and the time is 0.5~3h.

5. The method for recovering titanium from titanium-containing blast furnace slag as described in claim 1, characterized in that, In both steps (2) and (3), the solid-liquid separation methods are filtration or centrifugation.

6. The method for recovering titanium from titanium-containing blast furnace slag as described in claim 1, characterized in that, In step (4), the washing liquid is water, the washing temperature is 20~50℃, and the solid-liquid ratio of the hydrolyzed titanium slag to the washing liquid is 1:1~6.

7. The method for recovering titanium from titanium-containing blast furnace slag as described in claim 1, characterized in that, In step (4), the volume concentration of sulfuric acid is 10-70%; the second acid leaching temperature is 50-100℃ and the time is 0.5-3h; the solid-liquid ratio of the hydrolyzed titanium slag to sulfuric acid is 1:2-8.

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