A kind of pre-treatment method of sulfuric acid slag

Abstract

The present invention belongs to the technical field of industrial waste residue treatment, and discloses a pre-treatment method for sulfuric acid slag, wherein the pre-treatment method for sulfuric acid slag utilizes molten hydroxide to smelt sulfuric acid slag to remove oxides in the sulfuric acid slag; the method comprises: hydrothermally treating the sulfuric acid slag with molten hydroxide at a relatively low temperature; and removing the generated soluble salts by water washing and ultrasonic filtration. The present invention utilizes the low melting point of molten hydroxide to effectively remove oxides such as silicon, aluminum, zinc, and sulfur in the sulfuric acid slag at a relatively low temperature, thereby greatly achieving the enrichment of iron in the sulfuric acid slag. The sulfuric acid slag treated by the present invention has the characteristics of extremely low content of oxides such as silicon, aluminum, zinc, and sulfur, and the total iron content of the treated sulfuric acid slag is >60%.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial waste residue treatment, and in particular relates to a pre-treatment method for sulfuric acid residue. Background Art

[0002] At present, most of my country's sulfuric acid plants use pyrite as raw material, and a large amount of sulfuric acid slag is produced at the same time. According to incomplete statistics, more than 20 million tons of sulfuric acid slag are produced every year, accounting for about one-third of industrial solid waste, resulting in the accumulation of tens of millions of tons of sulfuric acid slag, leading to a large amount of land resources being wasted, and the heavy metals and sulfur-phosphorus compounds in the sulfuric acid slag will also seep into the soil and water, thereby damaging the ecological environment. There are also abundant iron resources in the sulfuric acid slag, which is also a favorable resource. The iron resource content in my country's sulfuric acid slag is about 30%-60%. Due to the large difference in the grade of pyrite, the composition and properties of sulfuric acid slag are also very different. The silicon and aluminum content in my country's sulfuric acid slag is relatively high. Therefore, it is of great practical significance to develop an economical pre-treatment method to increase the iron content of sulfuric acid slag.

[0003] Regarding the reuse of sulphuric acid slag, currently only sulphuric acid slag with a higher iron content can be processed as raw material for ironmaking. Due to the lack of professional knowledge of operators and the limitation of sales costs, low-grade sulphuric acid slag can only be sold after traditional water washing and panning; or directly stacked for treatment, which not only occupies land, but also wastes resources and pollutes the environment. Secondly, magnetic separation can also enrich iron concentrate in low-grade sulphuric acid slag. For example, patent 200510130928.2 discloses a treatment method for the separation and purification of sulphuric acid slag, which discloses a multi-process combined treatment method such as magnetic separation, magnetic separation-shaking table, and ore washing-classification-magnetic separation. However, magnetic separation requires more magnetic substances in sulphuric acid slag, and sulphuric acid slag is obtained through high-temperature treatment, mostly hematite, and the magnetic separation effect is not ideal.

[0004] Through the above analysis, the existing sulfate slag treatment methods are more effective for sulfate slag with higher iron grade, but there is still a lack of effective enrichment treatment methods for sulfate slag with lower iron grade and higher hematite content, and the overall resource recovery rate is not high. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a pre-treatment method for sulfuric acid slag.

[0006] The present invention is achieved by providing a pretreatment method for sulfuric acid slag, wherein the pretreatment method for sulfuric acid slag utilizes molten hydroxide to smelt the sulfuric acid slag to remove oxides in the sulfuric acid slag; the method comprises: hydrothermally treating the sulfuric acid slag with molten hydroxide at a relatively low temperature; removing the generated soluble salts by water washing and ultrasonic filtration, thereby removing part of the impurities in the sulfuric acid slag and achieving the enrichment of the iron content.

[0007] Furthermore, the hydrothermal treatment is preceded by:

[0008] Sodium hydroxide and potassium hydroxide were mixed in a mass ratio of 1:1.345, ground and placed at the bottom of the reactor;

[0009] A certain amount of sulfuric acid slag is weighed, wherein the mass ratio of the sulfuric acid slag to the mixed alkali is 1:1-10:1, and then placed on the top of the mixed alkali.

[0010] Furthermore, 5.1 g of sodium hydroxide and 6.86 g of potassium hydroxide were ground until they were evenly placed at the bottom of the reactor.

[0011] Further, 12 g of sulfuric acid slag was placed on the top of the mixed alkali.

[0012] Further, after the hydrothermal treatment:

[0013] The temperature is raised to 180-200° C. and the reaction is carried out at a suitable temperature for 1-10 hours. After the reaction is completed, a certain amount of water is added into the kettle, wherein the mass ratio of water to mixed alkali is 1:1-8:1.

[0014] Further, the reaction was carried out at 180°C for 3 hours.

[0015] Furthermore, the water-washing ultrasonic filtration is carried out for 0.5-10 hours of ultrasonic treatment, followed by filtration and washing with water until the solution is neutral.

[0016] Furthermore, after ultrasonic treatment for 1 hour, the solution was filtered and washed with water until the solution became neutral.

[0017] Furthermore, the oxide comprises silicon oxide, zinc oxide and aluminum oxide.

[0018] Furthermore, the soluble salts include silicates, zincates, sulfates and aluminates.

[0019] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0020] The present invention utilizes the low melting point of molten hydroxide to effectively remove oxides such as silicon, aluminum, zinc, sulfur, etc. in the sulfuric acid slag at a relatively low temperature, thereby greatly achieving the enrichment of iron in the sulfuric acid slag.

[0021] The beneficial effects of the present invention are: (1) the treated slag has the characteristics of extremely low content of oxides such as silicon, aluminum, zinc, and sulfur; and (2) the treated slag has a total iron content of >60%.

[0022] The expected benefits and commercial value of the technical solution of the present invention after conversion are as follows: the technical solution of the present invention can solve the problem of enriching the medium iron grade of sulfate slag with low iron grade and high hematite content after conversion, and make up for the problem that low-quality sulfate slag is difficult to be recycled in existing technologies. Once converted, the solution can not only solve the environmental problems caused by the current stacking of sulfate slag, but also convert low-quality sulfate slag into high-quality sulfate slag, so that it can be recycled as a mineral source for steelmaking, and has extremely high application prospects and commercial value.

[0023] The technical solution of the present invention fills the technical gap in the industry at home and abroad: the technical solution of the present invention fills the technical gap that low-quality sulfuric acid slag cannot be directly utilized as resources at home and abroad, can effectively reduce the content of silicon, aluminum, sulfur and heavy metal zinc in sulfuric acid slag, and realize the enrichment of medium iron grade in sulfuric acid slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a flow chart of a pre-treatment method for sulfuric acid slag provided by an embodiment of the present invention;

[0025] Figure 2 It is an X-ray diffraction (XRD) spectrum of the sulfate slag before and after treatment provided by the embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0027] In order to enable those skilled in the art to fully understand how to implement the present invention in detail, this section is an explanatory embodiment that expands and describes the technical solution of the claims.

[0028] like Figure 1 As shown, the pre-treatment method of sulfuric acid slag provided by the embodiment of the present invention comprises the following steps:

[0029] S101: mixing sodium hydroxide and potassium hydroxide in a mass ratio of 1:1.345, grinding until uniform, and placing at the bottom of a reaction kettle;

[0030] S102: weighing a certain amount of sulfuric acid slag, wherein the mass ratio of the sulfuric acid slag to the mixed alkali is controlled between 1:1-10:1, and then placing it on the top of the mixed alkali;

[0031] S103: raising the temperature to 180-200° C. and reacting at a suitable temperature for 1-10 hours; after the reaction is completed, adding a certain amount of water into the kettle, wherein the mass ratio of water to mixed alkali is controlled between 1:1-8:1;

[0032] S104: After ultrasonic treatment for 0.5-10 hours, filter and wash with water until the solution becomes neutral.

[0033] The pretreatment method of sulfuric acid slag provided in the embodiment of the present invention uses molten hydroxide to smelt sulfuric acid slag to quickly remove oxides such as silicon oxide and aluminum oxide in sulfuric acid slag, comprising: (1) firstly hydrothermally treating the sulfuric acid slag with molten hydroxide at a relatively low temperature. (2) then removing the generated soluble silicates, zincates, sulfates and aluminates by water washing and ultrasonic filtration.

[0034] In order to prove the creativity and technical value of the technical solution of the present invention, this section provides application examples of the claimed technical solution on specific products or related technologies.

[0035] Example 1

[0036] The pretreatment method of the sulfuric acid slag in the embodiment of the present invention comprises the following steps:

[0037] (1) Grind 5.1 g of sodium hydroxide and 6.86 g of potassium hydroxide until they are evenly placed at the bottom of the reactor;

[0038] (2) Place 12 g of sulfuric acid residue on top of the mixed alkali and react at 180°C for 3 h;

[0039] (3) After ultrasonic treatment for 1 hour, the mixture was filtered and washed with water until the solution became neutral.

[0040] Example 2

[0041] The pretreatment method of the sulfuric acid slag in the embodiment of the present invention comprises the following steps:

[0042] (1) Grind 51 kg of sodium hydroxide and 68.6 kg of potassium hydroxide until they are evenly placed at the bottom of the reactor;

[0043] (2) Place 120 kg of sulfuric acid residue on top of the mixed alkali and react at 200°C for 10 hours;

[0044] (3) After ultrasonic treatment for 3 hours, the mixture was filtered and washed with water until the solution became neutral.

[0045] The embodiments of the present invention have achieved some positive effects during the development or use process, and indeed have great advantages over the prior art. The following content is described in conjunction with data, charts, etc. of the test process.

[0046] like Figure 2 As shown, when the sulfate slag treated in Example 1 is compared with that before treatment, only the peak of iron oxide can be seen in the X-ray diffraction (XRD) spectrum of the sulfate slag after treatment.

[0047] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for pre-treating sulfuric acid slag, characterized in that: The pretreatment method of the sulfuric acid slag is to use molten hydroxide to smelt the sulfuric acid slag to remove oxides in the sulfuric acid slag; comprising: hydrothermally treating the sulfuric acid slag with molten hydroxide at a relatively low temperature; removing the generated soluble salts by water washing and ultrasonic filtration; The hydrothermal treatment requires: Sodium hydroxide and potassium hydroxide were mixed in a mass ratio of 1:1.345, ground and placed at the bottom of the reactor; Weigh a certain amount of sulfuric acid slag, wherein the mass ratio of the sulfuric acid slag to the mixed alkali is 1:1-10:1, and then place it on the top of the mixed alkali; The hydrothermal treatment requires: The temperature is raised to 180-200°C, and the reaction is carried out at a suitable temperature for 1-10 hours; after the reaction is completed, a certain amount of water is added to the kettle, wherein the mass ratio of water to mixed alkali is 1:1-8:1; The oxides include silicon oxide, zinc oxide and aluminum oxide.

2. The pre-treatment method of sulfuric acid slag according to claim 1, characterized in that: Grind 5.1 g of sodium hydroxide and 6.86 g of potassium hydroxide until they are evenly placed at the bottom of the reactor.

3. The pre-treatment method of sulfuric acid slag according to claim 1, characterized in that: Take 12g of sulfuric acid slag and place it on the top of the mixed alkali.

4. The pre-treatment method of sulfuric acid slag according to claim 1, characterized in that: React at 180°C for 3h.

5. The pre-treatment method of sulfuric acid slag according to claim 1, characterized in that: The water-washed ultrasonic filtration is carried out after ultrasonic treatment for 0.5-10 hours, and then filtered and washed with water until the solution is neutral.

6. The pre-treatment method of sulfuric acid slag according to claim 5, characterized in that: After ultrasonic treatment for 1 hour, the solution was filtered and washed with water until it became neutral.

7. The pre-treatment method of sulfuric acid slag according to claim 1, characterized in that: The soluble salts include silicates, zincates, sulfates and aluminates.

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