Efficient waste steel slag treatment process

Abstract

The invention provides an efficient waste steel slag treatment process, and relates to the technical field of waste steel slag treatment. The device based on efficient waste steel slag treatment comprises the following steps that S1, large steel slag is subjected to crushing, iron separation and grinding, and steel slag powder is obtained; s2, the steel slag powder is matched with a leaching agent for pulping leaching, and in the leaching process, CaO and a small amount of MgO components in the slag are decomposed and subjected to a chemical reaction with ammonium chloride; s3, carrying out solid-liquid separation to dissolve main alkaline components in the steel slag, and improving the separation efficiency by adopting a plate-and-frame pressure filtration method; through the process technical design, in the treatment process of the waste steel slag, the effects that the reaction temperature is low, the energy consumption is low, the dielectric loss is small, a medium does not react with FeO, the iron loss is small, the concentration of calcium and magnesium ions in a leached solution is high and the like can be achieved, and meanwhile a large amount of CO2 can be consumed; through a leaching process, a leaching reactor and a quantum ring activation process are adopted, so that the later reaction time can be shortened by about 70%, and the accident rate can be reduced by 80%.

Description

Technical Field

[0001] The invention relates to the technical field of waste steel slag treatment, in particular to a high-efficiency waste steel slag treatment process. Background Art

[0002] About 120 million tons of steel slag are produced in the steelmaking process, and the cumulative stockpile exceeds 1 billion tons. The large amount of steel slag storage not only occupies land resources, but also poses a major safety hazard to the ecological environment. At present, the rational use of steel solid waste is one of the keys to my country's comprehensive resource utilization, and accelerating the utilization of steel slag has also become a consensus of the whole society.

[0003] The treatment of waste steel slag is a difficult problem that needs to be solved in the steel industry. Many new technologies and processes have emerged at home and abroad, but most of them are difficult to promote and apply due to poor actual economic benefits. This new technology uses the calcium oxide component contained in waste steel slag as the calcium source and ammonium chloride solution as the reaction solvent. The carbonization process of indirect minerals obtained through leaching and carbonization reaction is currently the most advanced technology and process in China. It can produce high-purity light calcium carbonate products with high commercial value, iron ore powder containing 50%-55% iron, and silicon-aluminum slag that can be used as silicon fertilizer or building materials. At the same time, it also consumes a large amount of CO2, and the economic and social benefits are very significant. Summary of the invention

[0004] 1. Technical issues to be solved

[0005] In view of the shortcomings of the prior art, the present invention provides a high-efficiency treatment process for waste steel slag, which solves the problem that the process is difficult to promote and apply due to poor actual economic benefits.

[0006] (II) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions: A high-efficiency waste steel slag treatment process, comprising the following steps: S1, crushing, iron selection, grinding, and obtaining steel slag powder;

[0008] S2, mixing the steel slag powder with a leaching agent for pulping and leaching. During the leaching process, the CaO and a small amount of MgO components in the slag decompose and react chemically with ammonium chloride;

[0009] S3, then carry out solid-liquid separation to dissolve the main alkaline components in the slag, and use a plate and frame filter press method to improve the separation efficiency;

[0010] S4, carbonization of the filtrate, extracting a large amount of calcium ions and a small amount of magnesium ions in the filtrate, and the filtrate needs to be carbonized. After the carbonization reaction is completed, solid-liquid separation is performed again. The filter cake is a semi-finished product of calcium carbonate (containing a small amount of magnesium carbonate), which is dried, ground and packaged to be the product. The filtrate is returned to the leaching system for recycling;

[0011] S5, iron extraction from filter residue, the FeO is separated by magnetic separation, and the high magnetic Slon-1200 wet separation process is selected to ensure satisfactory recovery rate and concentrate grade, that is, recovery rate of 70%-75%, iron grade of 50%-55.0%, which is convenient for improving the treatment efficiency of scrap slag, reducing the production cost of equipment, and providing later economic benefits.

[0012] Preferably, the grinding process in S1 requires the slag powder fineness to be 150-200 meshes, so as to facilitate the subsequent processing of the steel slag powder and achieve the accuracy of the steel slag powder processing.

[0013] Preferably, the leaching agent in S2 is ammonium chloride solution, which is convenient for leaching the steel slag powder and facilitates the subsequent leaching and decomposition function.

[0014] Preferably, the reaction liquid needs to be activated by a quantum ring during the S2 leaching process to facilitate the solidification function of the liquid after the slag leaching, thereby achieving a state in which solid and liquid are simultaneously produced in the later stage of the slag powder, and the internal components of the solid and liquid have different properties, which is convenient for separation.

[0015] Preferably, the alkaline components in the S3 steel slag can be dissolved to generate CaCl2, NH4OH, and MgCl2, and the original components such as SiO2, Al2O3, FeO in the steel slag can remain in the steel slag as a solid phase, so that the decomposed components in the steel slag can be clearly identified, and the decomposed steel slag can also be separated and processed.

[0016] Preferably, a carbonization reactor is required in S4 to carry out the main carbonization reaction, so as to facilitate the carbonization reaction in the slag treatment process, and the source of CO2 is taken from the lime kiln of the steel plant, the flue gas of the sintering machine or the purchased liquid CO2 product.

[0017] Preferably, the main components of the steel slag leached from S5 are FeO, SiO2 and a small amount of Al2O3, which is convenient for reducing dielectric loss, and the medium does not react with FeO, thereby improving the quality of iron extraction in the later stage.

[0018] The CaO is calcium oxide, MgO is magnesium oxide, FeO is ferrous oxide, Sl on-1200 is a high gradient vertical ring strong magnetic separator, CaCl 2 is calcium chloride, NH 4 OH is ammonia monohydrate, MgCl 2 is magnesium chloride, SiO 2 is silicon dioxide, and Al 2 O 3 is aluminum oxide, which is convenient for marking chemical abbreviations.

[0019] (III) Beneficial effects

[0020] The present invention provides a highly efficient process for treating waste steel slag, which has the following beneficial effects:

[0021] 1. Through the design of this process technology, the waste steel slag will have low reaction temperature, low energy consumption, small medium loss, and the medium will not react with FeO, so the iron loss is small, and the concentration of calcium and magnesium ions in the leaching liquid is high. At the same time, it can also absorb a large amount of CO2, which is carbon dioxide.

[0022] 2. Through the leaching process, the use of leaching reactor and quantum ring activation technology can shorten the reaction time in the later stage by about 70% and reduce the accident rate by 80%.

[0023] 3. The use of carbonization reactor can effectively improve the carbonization efficiency by about 30%, and the equipment volume will also be reduced by 30%.

[0024] 4. Finally, through the advanced ammonium chloride recycling technology, the production cost is greatly reduced, and the economic benefits are significant. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a simplified diagram of the production process of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] like Figure 1 As shown, the embodiment of the present invention provides an efficient treatment process for waste steel slag, comprising the following steps: S1, crushing, iron selection, grinding, and obtaining steel slag powder;

[0028] S2, mixing the steel slag powder with a leaching agent for pulping and leaching. During the leaching process, the CaO and a small amount of MgO components in the slag decompose and react chemically with ammonium chloride;

[0029] S3, then carry out solid-liquid separation to dissolve the main alkaline components in the slag, and use a plate and frame filter press method to improve the separation efficiency;

[0030] S4, carbonization of the filtrate, extracting a large amount of calcium ions and a small amount of magnesium ions in the filtrate, and the filtrate needs to be carbonized. After the carbonization reaction is completed, solid-liquid separation is performed again. The filter cake is a semi-finished product of calcium carbonate (containing a small amount of magnesium carbonate), which is dried, ground and packaged to become the product. The filtrate is returned to the leaching system for recycling;

[0031] S5. Extract iron from filter residues. The FeO is separated by magnetic separation, and the high magnetic Slon-1200 wet separation process is selected to ensure satisfactory recovery rate and concentrate grade, that is, recovery rate of 70%-75% and iron grade of 50%-55.0%.

[0032] The grinding process in S1 requires the slag powder fineness to be 150-200 mesh.

[0033] The leaching agent in S2 is ammonium chloride solution.

[0034] During the S2 leaching process, the reaction solution needs to be activated by a quantum ring.

[0035] The alkaline components in the S3 steel slag can be dissolved to generate CaCl2, NH4OH, and MgCl2, and the original components such as SiO2, Al2O3, FeO in the steel slag can remain in the steel slag as a solid phase.

[0036] In S4, a carbonization reactor is required to carry out the main carbonization reaction.

[0037] The main components of the steel slag leached from S5 are FeO, SiO2 and a small amount of Al2O3.

[0038] The CaO is calcium oxide, MgO is magnesium oxide, FeO is ferrous oxide, Sl on-1200 is a high gradient vertical ring strong magnetic separator, CaCl 2 is calcium chloride, NH 4 OH is ammonia monohydrate, MgCl 2 is magnesium chloride, SiO 2 is silicon dioxide, and Al 2 O 3 is aluminum oxide.

[0039] Working principle: When using, the large steel slag can be crushed, iron selected, and ground into powder. The fineness of the steel slag powder should be 150-200 meshes during grinding. Then the steel slag powder is leached with ammonium chloride solution, so that the concentration of NH4C1 ammonium chloride is 26.5%, the solid-liquid ratio is 3:7, the reaction temperature is 45℃, and the reaction time is 45min. The above-mentioned dissolution equipment is mainly used as a leaching reactor. During the leaching process, the CaO and a small amount of MgO components in the steel slag are decomposed and react chemically with the ammonium chloride:

[0040] CaO+2NH4C l+H2O==CaC l2+2NH4OH,

[0041] MgO+2NH4C l+H2O==MgC l2+2NH4OH.

[0042] At the same time, due to the restriction of Cl content in the target product of this project, the reaction solution needs to be activated by quantum rings during the leaching process.

[0043] During solid-liquid separation, the main alkaline components in the steel slag can be dissolved through the leaching of ammonium chloride solution to generate CaCl2, NH4OH, and MgCl2, among which the original SiO2, Al2O3, FeO and other components can remain in the steel slag as a solid phase, and the plate and frame filter pressing method can be used during solid-liquid separation to achieve effective separation of solid and liquid. The main components of the filtrate are CaCl2, NH4OH, and MgCl2, and the main components of the filter residue are SiO2, Al 2O3, FeO, etc.

[0044] When the filtrate is carbonized and the residue is used to extract iron, the filtrate is carbonized to extract a large amount of calcium ions and a small amount of magnesium ions contained in the filtrate. At the same time, a carbonization reactor is required to carbonize the filtrate during the extraction process. The source of CO2 is taken from the lime kiln of the steel plant, the flue gas of the sintering machine or the purchased liquid CO2 product. The chemical reaction principle of the carbonization is:

[0045] CaCl 2+CO2+2NH4OH==CaCO3+2NH4C l+H2O,

[0046] MgCl 2+CO2+2NH4OH==MgCO3+2NH4C l+H2O.

[0047] After the carbonization reaction is completed, solid-liquid separation is carried out again. The filter cake is a semi-finished product of calcium carbonate (containing a small amount of magnesium carbonate). After drying, grinding and packaging, it becomes the product. The filtrate is returned to the leaching system for recycling.

[0048] Extract iron from leaching residue. The main components of the leaching residue are FeO, SiO2 and a small amount of Al2O3. In order to separate the FeO, magnetic separation is adopted. Considering the weak magnetic properties of FeO and the need to wash Cl, the high magnetic Slon-1200 wet separation process is preferably selected to ensure satisfactory recovery rate and concentrate grade, that is, recovery rate of 70%-75% and iron grade of 50%-55.0%.

[0049] According to the process characteristics of the project, three products can be produced:

[0050] 1. Ultrafine calcium carbonate powder: It is a very useful chemical substance with a wide range of uses. It can be used in food additives, pharmaceutical manufacturing, plastic manufacturing, coatings and paints, paper manufacturing and other fields. With the continuous development of science and technology, the application field of ultrafine calcium carbonate powder will continue to expand;

[0051] 2. Silicon aluminum powder: It has a wide range of applications, covering many fields such as construction, chemical industry, food processing and medicine;

[0052] 3. Iron ore concentrate is the main raw material for the steel industry. The iron ore concentrate with an iron content of 50%-55% produced by this project can be used as a raw material for sintering and pelletizing, and can also be used as a raw material for ore blending.

[0053] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-efficiency treatment process for waste steel slag, characterized in that: The following steps are involved: S1, crushing, iron selection, grinding of large pieces of steel slag to obtain steel slag powder; S2, mixing the steel slag powder with a leaching agent for pulping and leaching. During the leaching process, the CaO and a small amount of MgO components in the slag decompose and react chemically with ammonium chloride; S3, then carry out solid-liquid separation to dissolve the main alkaline components in the slag, and use a plate and frame filter press method to improve the separation efficiency; S4, carbonization of the filtrate, extracting a large amount of calcium ions and a small amount of magnesium ions in the filtrate, and the filtrate needs to be carbonized. After the carbonization reaction is completed, solid-liquid separation is performed again. The filter cake is a semi-finished product of calcium carbonate (containing a small amount of magnesium carbonate), which is dried, ground and packaged to be the product. The filtrate is returned to the leaching system for recycling; S5. Extract iron from filter residues. The FeO is separated by magnetic separation and the high magnetic Slon-1200 wet separation process is selected to ensure satisfactory recovery rate and concentrate grade, that is, recovery rate of 70%-75% and iron grade of 50%-55.0%.

2. The high-efficiency treatment process for waste steel slag according to claim 1, characterized in that: The grinding process in S1 requires the slag powder fineness to be 150-200 mesh.

3. The high-efficiency treatment process for waste steel slag according to claim 1, characterized in that: The leaching agent in S2 is ammonium chloride solution.

4. The high-efficiency treatment process for waste steel slag according to claim 1, characterized in that: During the S2 leaching process, the reaction solution needs to be activated by a quantum ring.

5. The efficient treatment process for waste steel slag according to claim 1, characterized in that: The alkaline components in the S3 steel slag can be dissolved to generate CaCl2, NH4OH, and MgCl2, and the original components such as SiO2, Al2O3, FeO in the steel slag can remain in the steel slag as a solid phase.

6. The high-efficiency treatment process for waste steel slag according to claim 1, characterized in that: In S4, a carbonization reactor is required to carry out the main carbonization reaction.

7. The high-efficiency treatment process for waste steel slag according to claim 1, characterized in that: The main components of the steel slag leached from S5 are FeO, SiO2 and a small amount of Al2O3.

8. A process for efficiently treating waste steel slag according to any one of claims 1 to 7, characterized in that: The CaO is calcium oxide, MgO is magnesium oxide, FeO is ferrous oxide, Slon-1200 is a high gradient vertical ring strong magnetic separator, CaCl2 is calcium chloride, NH4OH is ammonia monohydrate, MgCl2 is magnesium chloride, SiO2 is silicon dioxide, and Al2O3 is aluminum oxide.

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