Desulfurization method of high-sulfur bauxite

Abstract

The invention belongs to the field of metallurgy, and particularly relates to a desulfurization method of high-sulfur bauxite. The invention relates to a desulfurization method of high-sulfur bauxite, which comprises the following steps: (1) crushing and screening the high-sulfur bauxite, and selecting high-sulfur bauxite powder; (2) dissolving the high-sulfur bauxite powder in the step (1) with a sodium hydroxide solution to form bauxite ore pulp, introducing the bauxite ore pulp into an electrolytic bath, and introducing the bauxite ore pulp into a cathode and an anode by taking sodium hydroxide as an electrolyte and hydrogen peroxide as an oxidant in the electrolytic bath; and (3) electrolyzing the sodium hydroxide medium of the bauxite by setting the cell voltage, the current intensity and the electrolysis temperature of the electrolytic cell in the step (2). Solid sulfur in the high-sulfur bauxite is electrolyzed by adopting the sodium hydroxide solution of the high-sulfur bauxite as an electrolyte, hydrogen peroxide as an oxidizing agent and graphite as a cathode and an anode, the solid sulfur is oxidized into soluble sulfur to complete desulfurization, and the method has the technical advantages of low temperature, normal pressure, high desulfurization rate and no secondary pollution.

Description

Technical Field

[0001] The present invention belongs to the field of metallurgy, and particularly relates to a desulfurization method for high-sulfur bauxite. Background Art

[0002] China is the world's largest producer of alumina (Al2O3). In 2023, the alumina output was approximately 82.44 million tons, accounting for about 58% of the global total output. However, China is not a country rich in bauxite resources. The basic reserves of bauxite only account for about 3% of the global bauxite reserves, and mainly consist of medium- and low-grade diaspore-type bauxite. Currently, the production of alumina in China mainly relies on the import of high-quality bauxite, with an external dependence as high as 60%. Bauxite resources have been listed as scarce mineral resources in China.

[0003] Large amounts of high-sulfur bauxite resources in China are distributed in provinces such as Yunnan, Guizhou, Sichuan, and Henan, with an overall reserve of approximately 2 billion tons and a sulfur content exceeding 0.7%. An increase in the sulfur content in bauxite will lead to a series of problems, such as a decrease in the alumina digestion rate, difficulty in solution desilication, deterioration of product quality, reduction of seed precipitation efficiency, vessel scaling, corrosion of steel pipes, and difficulty in red mud washing and separation. Therefore, the desulfurization technology for high-sulfur bauxite has become the key to realizing its efficient comprehensive utilization and alleviating the shortage of bauxite resources in China.

[0004] The development and utilization of high-sulfur bauxite is an important way to reduce China's high dependence on foreign bauxite resources and ensure the sustainable development of China's alumina industry. Currently, the reserves of diaspore-type high-sulfur bauxite in China are 800 million tons, and the prospective reserves are approximately 2 billion tons, mainly distributed in places such as Henan, Guizhou, Guangxi, and Chongqing. Among them, high-sulfur bauxite with an alumina-silica ratio (A / S) of 4 - 7 accounts for more than half.

[0005] Therefore, the large-scale development and utilization of high-sulfur bauxite must first solve the problem of desulfurization. The desulfurization methods for high-sulfur bauxite are mainly divided into two categories: one is pre-treatment desulfurization before bauxite digestion, mainly including ore dressing desulfurization, roasting desulfurization, microbial desulfurization, etc.; the advantage of pre-treatment desulfurization is that it can reduce sulfur entering the production process from the source, thereby reducing the impact of sulfur on the alumina production process, and the disadvantage is that the production process becomes longer and the production cost increases; the other is desulfurization during the alumina production process, that is, desulfurization by adding a desulfurizing agent in the Bayer process. Process desulfurization can select the desulfurization site according to the distribution of sulfur in the alumina production process in a timely manner, and the disadvantage is that the requirements for the desulfurizing agent are relatively high, and the desulfurization effect is greatly affected by the composition of the sodium aluminate solution.

[0006] Therefore, there is an urgent need to provide a technical solution to address the deficiencies of the above-mentioned existing technologies. Summary of the Invention

[0007] In order to overcome the deficiencies of the prior art, the present invention provides a desulfurization method for high-sulfur bauxite with low temperature, normal pressure, high desulfurization rate and no secondary pollution.

[0008] In order to achieve the above object, a desulfurization method for high-sulfur bauxite provided by the present application adopts the following technical scheme: A desulfurization method for high-sulfur bauxite, comprising the following steps: (1) After the high-sulfur bauxite is crushed and screened, high-sulfur bauxite powder is selected; (2) The high-sulfur bauxite powder in step (1) is dissolved with sodium hydroxide solution to form bauxite slurry, and the bauxite slurry is introduced into an electrolytic cell. In the electrolytic cell, sodium hydroxide is used as the electrolyte and hydrogen peroxide is used as the oxidant, and is introduced into the cathode and anode; (3) Set the cell voltage, current intensity, and electrolysis temperature of the electrolytic cell in step (2) to electrolyze the sodium hydroxide medium of the bauxite.

[0009] Preferably, in step (1), the particle size of the high-sulfur bauxite powder is less than 50 μm.

[0010] Preferably, in step (1), the sulfur content in the high-sulfur bauxite is 1-10%.

[0011] Preferably, in step (2), the concentration of the sodium hydroxide is 2-5 mol / L.

[0012] Preferably, in step (2), the concentration of the bauxite slurry is 0.2-0.6 g / L.

[0013] Preferably, in step (2), the concentration of the hydrogen peroxide is 0.4-0.8 mL / L.

[0014] Preferably, in step (2), the materials of the cathode and anode are both graphite.

[0015] Further preferably, in step (3), the cell voltage is 3-5 V and the current intensity is 1.2-2.0 A.

[0016] Even more preferably, the electrolysis temperature is 50-70 °C and the electrolysis time is 2-4 h.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The electrolytic desulfurization of the present invention uses the method of electrochemical oxidation to oxidize the solid sulfur in the mineral into soluble sulfur to complete desulfurization. The present invention has the technical advantages of low temperature, normal pressure, high desulfurization rate and no secondary pollution.

[0018] (2) Sulfur in high-sulfur bauxite exists in the form of iron disulfide. Under the action of an electric field, highly reactive free radicals O - and ·OH are generated during the electrolysis of hydrogen peroxide (H2O2) in an alkaline medium, which can promote the oxidation of inorganic sulfur in pyrite in bauxite into sulfate to complete sulfur removal.

[0019] (3) In the present invention, electrolysis and oxidation achieve a synergistic desulfurization effect, which is beneficial to shortening the reaction time and improving the technical advantages of production efficiency. Detailed implementation manners

[0020] The present application will be described in detail below in conjunction with embodiments. Each example is provided by way of explanation of the present application rather than limitation. In fact, those skilled in the art will clearly understand that modifications and variations can be made to the present application without departing from the scope or spirit of the present application. For example, features shown or described as part of one embodiment can be used in another embodiment to yield yet another embodiment. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention shall fall within the scope of protection of the embodiments of the present invention.

[0021] Example 1 A desulfurization method for high-sulfur bauxite, comprising the following steps: (1)Crush high-sulfur bauxite with a sulfur content of 3.86% into powder with a particle size of 45μm.

[0022] (2)Dissolve the high-sulfur bauxite powder with sodium hydroxide solution to form a bauxite pulp and then introduce it into an electrolytic cell. Among them, the concentration of the sodium hydroxide solution is 5mol / L, the concentration of the bauxite pulp is 0.6g / L, hydrogen peroxide is used as an oxidant, and the concentration of hydrogen peroxide is 0.8mL / L. The cathode and anode materials are graphite. Set the cell voltage to 5V, the current intensity to 2.0A, the electrolysis temperature to 70°C, and electrolyze for 4h. Then, after solid-liquid separation, dry the ore sample.

[0023] Analyze the sulfur content in the dried ore sample, and the desulfurization rate is 94%.

[0024] Example 2 A desulfurization method for high-sulfur bauxite, comprising the following steps: (1)Crush high-sulfur bauxite with a sulfur content of 3.27% into powder with a particle size of 35μm. (2) After dissolving the high-sulfur bauxite powder with sodium hydroxide solution to form a bauxite slurry, it is introduced into the electrolytic cell. Among them, the concentration of the sodium hydroxide solution is 4 mol / L, the concentration of the bauxite slurry is 0.4 g / L, hydrogen peroxide is used as the oxidant, and the concentration of hydrogen peroxide is 0.6 mL / L. The cathode and anode are made of graphite. Set the cell voltage to 4 V, the current intensity to 1.8 A, the electrolysis temperature to 60 °C, and electrolyze for 3 h. Then, after solid-liquid separation, the ore sample is dried.

[0025] Analyze the sulfur content in the dried ore sample, and the desulfurization rate is 93.5%.

[0026] Example 3 A desulfurization method for high-sulfur bauxite includes the following steps: Crush the high-sulfur bauxite with a sulfur content of 2.86% into a powder of 30 μm, dissolve the high-sulfur bauxite powder with sodium hydroxide solution and introduce it into the electrolytic cell. Graphite is used as the cathode and anode. In the electrolytic cell, the concentration of sodium hydroxide is 4 mol / L, the concentration of the bauxite slurry is 0.4 g / L, and the concentration of hydrogen peroxide is 0.4 mL / L. The cathode and anode are made of graphite. Set the cell voltage to 3 V, the current intensity to 1.2 A, the electrolysis temperature to 20 °C, and electrolyze for 2 hours. After solid-liquid separation, analyze the sulfur content of the dried ore sample, and the desulfurization rate is 92.8%.

[0027] Sulfur in high-sulfur bauxite exists in the form of ferrous disulfide. Under the action of an electric field, hydrogen peroxide (H2O2) generates highly reactive free radicals O - and ·OH during the electrolysis process in an alkaline medium, which can promote the oxidation of inorganic sulfur in pyrite in bauxite into sulfate to complete sulfur removal.

[0028] The present invention uses the sodium hydroxide solution of high-sulfur bauxite as the electrolyte, hydrogen peroxide as the oxidant, and graphite as the cathode and anode to electrolyze the solid sulfur in high-sulfur bauxite, oxidize the solid sulfur into soluble sulfur to complete desulfurization. In the present invention, electrolysis and oxidation achieve a synergistic desulfurization effect, which is beneficial to shortening the reaction time and improving the technical advantage of production efficiency. The present invention has the technical advantages of low temperature, normal pressure, high desulfurization rate, and no secondary pollution.

[0029] In the present invention, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0030] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A desulfurization method for high-sulfur bauxite, characterized in that It includes the following steps: (1) After crushing and screening the high-sulfur bauxite, select the high-sulfur bauxite powder; (2) Dissolve the high-sulfur bauxite powder in step (1) with sodium hydroxide solution to form a bauxite slurry, and introduce the bauxite slurry into an electrolytic cell. In the electrolytic cell, use sodium hydroxide as the electrolyte and hydrogen peroxide as the oxidant, and introduce them into the cathode and anode; (3) Set the cell voltage, current intensity, and electrolysis temperature in the electrolytic cell in step (2) to electrolyze the sodium hydroxide medium of the bauxite.

2. The desulfurization method of high-sulfur bauxite according to claim 1, characterized in that, In step (1), the particle size of the high-sulfur bauxite powder is less than 50 μm.

3. The desulfurization method of high-sulfur bauxite according to claim 1, wherein, In step (1), the sulfur content in the high-sulfur bauxite is 1-10%.

4. The desulfurization method of high-sulfur bauxite according to claim 1, wherein In step (2), the concentration of the sodium hydroxide is 2-5 mol / L.

5. The desulfurization method of high-sulfur bauxite according to claim 1, characterized in that In step (2), the concentration of the bauxite slurry is 0.2-0.6 g / L.

6. The desulfurization method of high-sulfur bauxite according to claim 1, characterized in that, In step (2), the concentration of the hydrogen peroxide is 0.4-0.8 mL / L.

7. The desulfurization method of high-sulfur bauxite according to claim 1, characterized in that, In step (2), the materials of the cathode and anode are both graphite.

8. The desulfurization method of high-sulfur bauxite according to any one of claims 1 to 7, characterized in that, In step (3), the cell voltage is 3-5 V, and the current intensity is 1.2-2.0 A.

9. The desulfurization method of high-sulfur bauxite according to claim 8, characterized in that, The electrolysis temperature is 50-70 °C, and the electrolysis time is 2-4 h.