阅读说明：本技术 一种采用铝熔盐电解还原处置冶炼渣的方法 (Method for treating smelting slag by electrolytic reduction of aluminum molten salt ) 是由 陈国宝 马云瑞 高世雄 高富聪 于 2019-11-27 设计创作，主要内容包括：本发明涉及含铁硅的冶炼废渣处置技术,具体提供一种采用铝熔盐电解还原处置冶炼渣的方法,该方法的工艺过程为先对除冶炼渣外的原料充分干燥脱水,将铝熔盐投入带集气罩的电解槽中升温加热,再按照比例依次加入辅料和冶炼渣混熔形成熔体,插入电极通入直流电在一定的温度和电压下进行还原反应,反应结束后熔渣层和液态金属层可通过放渣口和放液后导出形成产品,熔盐介质可以循环使用。本发明具有工艺简单、金属还原彻底、废渣大幅减量化和资源化、过程能利用冶炼渣物理显热、节能环保等优点。(The invention relates to a technology for treating smelting slag containing iron and silicon, and particularly provides a method for treating smelting slag by adopting electrolytic reduction of molten aluminum salt. The method has the advantages of simple process, thorough metal reduction, great reduction and recycling of waste slag, energy conservation, environmental protection and the like, and the smelting slag can be utilized in the process.)

1. A method for treating smelting slag by adopting aluminum molten salt electrolytic reduction is characterized by comprising the following steps: adding smelting slag, molten aluminum salt and auxiliary materials into a molten salt electrolysis device in proportion, wherein the mass fractions of the smelting slag, the molten aluminum salt and the auxiliary materials in the total feeding mass are respectively 10-80%, 10-80% and 5-80%, and carrying out molten salt electrolysis reduction under the conditions that the molten salt electrolysis temperature is 700-1600 ℃, the electrolysis time is 0.5-10 h and the electrolysis voltage is 2.0-4.0V, and separating different melts after the molten salt electrolysis is finished.

2. The method for treating smelting slag by adopting the electrolytic reduction of molten aluminum salt according to claim 1, characterized in that: the smelting slag contains iron and silicon, and specifically comprises one or more of copper-containing slag produced in copper smelting, blast furnace slag produced in steel smelting, converter slag, red mud formed in aluminum oxide production process, gold cyaniding tailings, lead-zinc smelting slag, laterite smelting nickel-iron slag and aluminum ash.

3. The method for treating smelting slag by adopting the electrolytic reduction of molten aluminum salt according to claim 1, characterized in that: the molten aluminum salt is cryolite-alumina solution, and the cryolite and the alumina account for 65-95% of the molten salt solution and 5-35% of the molten salt solution respectively in mass percent.

4. The method for treating smelting slag by adopting the electrolytic reduction of molten aluminum salt according to claim 1, characterized in that: the auxiliary material is a mixture of chloride, fluoride, hydroxide and carbonate, and the mass fractions of the chloride, the fluoride, the hydroxide and the carbonate in the total mass of the auxiliary material are respectively 30-85%, 5-30%, 5-40% and 5-40%.

5. The method for treating smelting slag by electrolytic reduction of molten aluminum salt according to claim 4, wherein: the chloride is one or more of sodium chloride, magnesium chloride, potassium chloride, calcium chloride and aluminum chloride; the fluoride is one or more of aluminum fluoride, calcium fluoride and magnesium fluoride; the hydroxide is one or more of sodium hydroxide, potassium hydroxide and calcium hydroxide; the carbonate is one or more of sodium carbonate, potassium carbonate and calcium carbonate.

6. The method for treating smelting slag by adopting the electrolytic reduction of molten aluminum salt according to claim 1, characterized in that: in the method, an anode used for electrolysis is one of a graphite anode and an oxide inert anode, a cathode is graphite, and the electrolytic cell is an aluminum electrolytic cell with a flue gas collecting cover.

7. The method for treating smelting slag by adopting the electrolytic reduction of molten aluminum salt according to claim 1, characterized in that: in the method, raw materials except smelting slag, molten aluminum salt and auxiliary materials are fully dried and dehydrated before feeding, and the water content is less than 0.1 percent.

8. The method for treating smelting slag by adopting the electrolytic reduction of molten aluminum salt according to claim 1, characterized in that: the method comprises the following steps of adding smelting slag, molten aluminum salt and auxiliary materials: adding molten aluminum salt into a molten salt electrolysis device, heating to melt, adding auxiliary materials, finally adding smelting slag, carrying out mixed melting to form a melt, adding the smelting slag which is molten or dried solid slag before adding, and electrifying direct current to carry out electrolysis after uniform mixed melting.

9. The method for treating smelting slag by adopting the electrolytic reduction of molten aluminum salt according to claim 1, characterized in that: after the reduction of the molten salt by electrolysis is finished, the molten salt is mixed to form three layers of melt, the upper layer is a molten salt layer, the middle layer is a slag layer, the lower layer is a liquid metal layer, and the slag layer and the liquid metal layer can be led out to form a product after passing through a slag tap and tapping.

10. The method for treating smelting slag by molten aluminum salt electrolytic reduction according to claim 9, wherein: the molten salt medium in the slag layer can be recycled, the new aluminum molten salt and the auxiliary materials are added from the top of the bath according to the mass ratio, and the new smelting slag is added from the side of the bath.

Technical Field

The invention belongs to the field of smelting waste residue treatment, and particularly relates to a method for treating smelting slag by electrolytic reduction of aluminum molten salt.

Background

With the rapid development of the metallurgical industry, the resource and environment problems faced by the industry are increasingly prominent, and the metallurgical industry becomes the life line of smelting enterprises in China. The metal smelting slag has the characteristics of complex components, great environmental hazard and the like, belongs to bulk industrial solid waste, and is difficult to treat and dispose solid waste by comprehensive utilization, such as colored smelting slag, copper slag, lead-zinc slag, red mud, nickel-iron slag, vanadium-iron slag and the like, and black smelting slag, such as steel slag, blast furnace slag, ferromanganese slag and the like. According to statistics, about 2-3 t of slag is generated when 1t of refined copper is generated, millions of tons of solid wastes are produced every year by copper smelting enterprises in China, and the stockpiling amount reaches hundreds of millions of tons every year; about 0.8-1.8 t of red mud is generated when 1t of alumina is produced, about 0.8 hundred million of red mud is discharged every year in China, and the accumulated stock exceeds 3.5 hundred million; in 2018, the production amount of steel slag in China reaches 1.21 hundred million tons, the comprehensive utilization rate of the steel slag is only about 30 percent, and from the beginning of the last 90 th century to the end of 2018, the accumulated stock of the steel slag tailings in China exceeds 18 million tons, and the occupied land is more than 20 mu of ten thousand. The components of the smelting slag often contain iron silicate, fayalite, oxides of iron, silicon, aluminum, magnesium and the like, certain gangue and the like, the iron content of the smelting slag is often higher than the industrial mining grade, and the smelting slag is an artificial mine with high utilization value. At present, because the impurity components in the smelting slag are complex, only a small part of the smelting slag can be used for preparing building materials, cement, road building and the like, and iron resources and the like contained in the smelting slag cannot be recycled.

In the traditional industry, smelting slag such as copper slag is subjected to flotation treatment of tailings after pyrogenic dilution, because flotation dilution occupies a large amount of land and has high requirements on the properties of the slag, the site requirements cannot be met by small-sized smelting plants, the smelting slag can only be sold for treatment, and the transportation cost greatly increases the recovery cost; and even if the dilution degree is higher, the metal content of the final slag is too high to be reused. The iron oxide with high content in the steel slag, especially the FeO with high content has a preparation effect on the subsequent use of the steel slag, the FeO can not be separated by magnetic separation, and the FeO does not have any hydration activity. At present, steel enterprises mainly adopt three treatment modes of roller type, tank type hot smoldering and slag pressing and hot braising treatment by steel slag waste heat to treat discharged steel slag, and can carry out magnetic separation iron extraction on the steel slag and prepare an excitant for cement and the like after the steel slag is cooled. Red mud and the like are usually subjected to reduction roasting magnetic separation and the like, and because of the lack of an economic and proper recycling process, alumina plants in China mostly adopt an open dam construction mode to pile up the red mud, the disposal mode not only occupies a large amount of land and wastes resources, but also causes underground water and soil pollution because alkali in the red mud can permeate underground; dust formed by the naked red mud is scattered along with wind, and can pollute the atmosphere, negatively affect the survival of human beings, animals and plants and worsen the ecological environment

In addition, smelting slag such as copper slag, steel slag and the like not only contains various beneficial mineral components, but also contains a large amount of sensible heat resources. For example, the specific heat capacity of the molten steel slag is about 1.2k J/(kg. DEG C.), and if the temperatures of the slag before and after heat recovery are respectively 1400 ℃ and 400 ℃, sensible heat of 1.2GJ can be recovered per ton of the steel slag, which is about 41kg of standard coal heat. The existing mainstream treatment process of copper slag, steel slag and the like can hardly utilize the sensible heat of smelting slag.

Therefore, if the resources such as iron, copper and the like in the smelting slag can be effectively separated and extracted, and the heavy metal components, the quantity and the like of the smelting slag are reduced, a large amount of iron resources can be provided for the metallurgy industry of China, and the method has very important significance for reduction of the smelting slag and efficient utilization of the resources.

Disclosure of Invention

Aiming at the defects of incomplete reduction of smelting slag, large amount of waste slag, difficult resource utilization of waste slag, low sensible heat utilization rate of smelting slag and the like in the prior art, the invention aims to provide the method for treating the smelting slag by adopting electrolytic reduction of the molten aluminum salt, and the method has the advantages of high reduction speed, one-step formation of high-grade metal products, short regeneration process, utilization of sensible heat of the smelting slag, small environmental pollution and the like.

The purpose of the invention is realized by the following technical scheme: a method for treating smelting slag by adopting aluminum molten salt electrolytic reduction comprises the following steps: adding smelting slag, molten aluminum salt and auxiliary materials into a molten salt electrolysis device in proportion, wherein the mass fractions of the smelting slag, the molten aluminum salt and the auxiliary materials in the total feeding mass are respectively 10-80%, 10-80% and 5-80%, and carrying out molten salt electrolysis reduction under the conditions that the molten salt electrolysis temperature is 700-1600 ℃, the electrolysis time is 0.5-10 h and the electrolysis voltage is 2.0-4.0V, and separating different melts after the molten salt electrolysis is finished.

Further, the smelting slag is iron and silicon containing smelting slag, and specifically comprises one or more of copper-containing slag generated in copper smelting, blast furnace slag generated in steel smelting, converter slag, red mud formed in aluminum oxide production process, gold cyaniding tailings, lead-zinc smelting slag, laterite smelting nickel-iron slag and aluminum ash.

Further, the molten aluminum salt is cryolite-alumina solution, and the cryolite and the alumina account for 65-95% of the molten salt solution and 5-35% of the molten salt solution respectively in mass percent.

Further, the auxiliary material is a mixture of chloride, fluoride, hydroxide and carbonate, and the mass fractions of the chloride, the fluoride, the hydroxide and the carbonate in the total mass of the auxiliary material are respectively 30-85%, 5-30%, 5-40% and 5-40%.

Further, the chloride is one or more of sodium chloride, magnesium chloride, potassium chloride, calcium chloride and aluminum chloride; the fluoride is one or more of aluminum fluoride, calcium fluoride and magnesium fluoride; the hydroxide is one or more of sodium hydroxide, potassium hydroxide and calcium hydroxide; the carbonate is one or more of sodium carbonate, potassium carbonate and calcium carbonate.

Further, the anode used in the electrolysis is one of a graphite anode and an oxide inert anode, the cathode is graphite, and the electrolysis bath is an aluminum electrolysis bath with a flue gas collecting cover.

Furthermore, the raw materials except the smelting slag, the molten aluminum salt and the auxiliary materials are fully dried and dehydrated before feeding, and the water content is less than 0.1 percent.

Further, in the method, the adding mode of the smelting slag, the molten aluminum salt and the auxiliary materials is as follows: adding molten aluminum salt into a molten salt electrolysis device, heating to melt, adding auxiliary materials, finally adding smelting slag, carrying out mixed melting to form a melt, adding the smelting slag which is molten or dried solid slag before adding, and electrifying direct current to carry out electrolysis after uniform mixed melting.

Further, after the molten salt electrolysis reduction is finished, the mixed molten salt forms three layers of melt, the upper layer is a molten salt layer, the middle layer is a molten slag layer, the lower layer is a liquid metal layer, and the molten slag layer and the liquid metal layer can be led out through a slag tap and tapping to form a product.

Furthermore, in the method, the molten salt medium in the molten salt layer can be recycled, the fresh molten aluminum salt and the auxiliary materials are added from the top of the tank according to the mass ratio, and the fresh smelting slag is added from the side of the tank.

Different from other molten salt reaction characteristics, the reduction process of the invention is characterized in that an electroreduction reaction, a thermite reduction reaction and a high-temperature ore phase reconstruction reaction occur simultaneously, and the related possible reactions mainly comprise:

2Al³⁺+6e→2Al

Cu²⁺+2e→Cu

Pb²⁺+2e→Pb

Fe³⁺+3e→Fe

Fe²⁺+2e→Fe

Si⁴⁺+4e→Si

Au⁺+e→Au

V⁵⁺+5e→V

Zr⁴⁺+4e→Zr

Cr³⁺+3e→Cr

Li⁺+e→Li

S^2-+2e→S

AlF₄ ^-+3e→Al+4F^-

AlF₆ ^-+3e→Al+6F^-

2O^2-+C→CO₂+4e

Al₂O₃+1.5C→2Al+1.5CO₂

2Al+Fe₂O₃→2Fe+Al₂O₃

4Al+3SiO₂→3Si+2Al₂O₃

2Al+3FeO→3Fe+Al₂O₃

2Al+3MnO→3Mn+Al₂O₃

4Al+3TiO₂→3Ti+2Al₂O₃

CaCO₃→CaO+CO₂

CaO+Fe₂SiO₄→CaSiO₃+2FeO

3CaO·SiO₂+3CO₂→3CaCO₃+SiO₂

2CaO·SiO₂+2CO₂→2CaCO₃+SiO₂

Na₂O·Al₂O₃·xSiO₂+3CaO→3CaO·Al₂O₃·xSiO₂+Na₂O

3CaO·Al₂O₃·xSiO₂+(3-x)CO₂→xCaO·SiO₂+(3-x)CaCO₃+3Al₂O₃

compared with the prior art, the invention has the following remarkable advantages:

1. the method adopts electrolytic reduction and high-temperature aluminum reduction, and because the aluminum has strong reducibility and the electroreduction has selectivity, the treatment of the smelting slag has the advantages of high reduction efficiency, controllable reduction process, thorough reduction, high impurity separation efficiency, low impurity content of metal products, high added value and the like;

2. the auxiliary materials used in the invention have the effect of modification, can accelerate the phase transformation of the smelting slag and lead the iron-silicon compound of the smelting slag which is difficult to dissociate quickly;

3. in the reduction process, aluminum can be repeatedly reduced and oxidized, so that the process has low raw material consumption and high economical efficiency;

4. the treatment process of the smelting slag is energy-saving, the process of the invention can absorb the physical sensible heat of the smelting slag such as copper slag, steel slag, blast furnace slag and the like, and the aluminum reacts with oxides in the slag to release a large amount of heat in the reduction process, so the energy consumption of the smelting slag aluminum electrolysis reduction process is low;

5. according to the invention, copper, iron, silicon and the like in the smelting slag form products, so that the quantity of the smelting slag can be greatly reduced while the metal grade in the slag is reduced, and reduction and recycling can be realized simultaneously;

in conclusion, the method has the advantages of simple process, thorough metal reduction, great reduction and resource utilization of waste slag, energy conservation, environmental protection and the like, and the smelting slag can be utilized in the process.

Drawings

FIG. 1 is a schematic flow chart of a method for treating smelting slag by electrolytic reduction of molten aluminum salt.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. The method flow of the present invention is shown in fig. 1, it should be understood that the specific embodiments described herein are only for the purpose of illustrating the present invention and are not to be construed as limiting the present invention.