阅读说明：本技术 贫铁高铝物料加碱增钙的液态熔融烧结-冷淬方法 (Liquid-state melt sintering-cold quenching method for adding alkali and increasing calcium to lean iron and high aluminum material ) 是由 张绪祎 杨海瑞 邵海杰 于 2021-01-20 设计创作，主要内容包括：本发明公开了一种贫铁高铝物料加碱增钙的液态熔融烧结-冷淬方法,其中,所述方法包括：(1)将贫铁高铝物料与碱和石灰石混合进行熔化烧结,以便得到熔化液态物料；(2)将所述熔化液态物料进行冷淬,以便得到固体颗粒；(3)将所述固体颗粒磨细后进行稀碱溶出,以便得到富钙尾粉以及含有铝酸钠的溶液。该方法采用熔化烧结和冷淬工艺对贫铁高铝物料进行处理,可以在不用湿磨以及不需要十分细小的粒度、缩短反应时间的同时降低能耗和提高铝回收率。(The invention discloses a liquid-state melt sintering-cold quenching method for adding alkali and increasing calcium to a lean iron and high aluminum material, wherein the method comprises the following steps: (1) mixing the lean iron and high aluminum material with alkali and limestone to perform melting sintering so as to obtain a molten liquid material; (2) performing cold quenching on the molten liquid material to obtain solid particles; (3) and (3) grinding the solid particles, and then dissolving out dilute alkali to obtain calcium-rich tail powder and a solution containing sodium aluminate. The method adopts the processes of melting sintering and cold quenching to process the lean iron and high aluminum materials, and can reduce energy consumption and improve the recovery rate of aluminum while avoiding wet grinding and fine granularity and shortening reaction time.)

1. A liquid-state melt sintering-cold quenching method for adding alkali and increasing calcium to a lean iron and high aluminum material is characterized by comprising the following steps:

(1) mixing the lean iron and high aluminum material with alkali and limestone to perform melting sintering so as to obtain a molten liquid material;

(2) performing cold quenching on the molten liquid material to obtain solid particles;

(3) and (3) grinding the solid particles, and then dissolving out dilute alkali to obtain calcium-rich tail powder and a solution containing sodium aluminate.

2. The method according to claim 1, wherein in step (1), the iron content of the iron-depleted high-alumina material is not higher than 7 mass%, and the alumina content is not lower than 20 mass%.

3. The method according to claim 1, wherein in the step (1), the iron-poor high-alumina material is a residual material obtained by recovering 10-30 mass% of ferric oxide in the total amount of bauxite or a residual material obtained by recovering 20-50 mass% of ferric oxide in the total amount of a mixed material comprising red mud and bauxite.

4. The method according to claim 3, wherein in step (1), the red mud in the mixed material comprising red mud and bauxite accounts for 10-70%, preferably 40-60% of the total weight of the mixed material.

5. The method according to any one of claims 1 to 4, wherein in step (1), the alkali comprises sodium hydroxide and/or sodium carbonate, and the addition amount of the alkali is (0.8-1.2) in terms of the molar ratio of the content of sodium oxide to the content of aluminum oxide in the iron-depleted high-alumina material: 1, preferably (0.9-1): 1.

6. the method according to claim 1, wherein in step (1), the limestone is added in an amount of 2 to 2.8 times the equivalent weight of the sum of silica and titania in the iron-depleted high-alumina material.

7. The method of claim 1, wherein in step (1), the melt-sintering apparatus is a melt furnace.

8. The method according to claim 1, wherein in the step (1), the melt sintering temperature is 1150-1400 ℃.

9. The method of claim 1, wherein in step (2), the quenching rate is not less than 500 ℃/s.

10. The method according to claim 1 or 9, wherein in step (2), the solid particles have a particle size of not more than 5 mm.

Technical Field

The invention belongs to the technical field of nonferrous metals, and particularly relates to a liquid-state fusion sintering-cold quenching method for adding alkali and increasing calcium to a lean iron high-aluminum material.

Background

The yield of the alumina in the world is over 50 percent in China, the main raw material for producing the alumina is bauxite, and the traditional alumina production process is a Bayer process, a rotary kiln sintering process and a combination method integrating the characteristics of the Bayer process and the rotary kiln sintering process. The dissolution temperature of bauxite processed by the Bayer process is usually 150 ℃ to 250 ℃, and the equipment pressure is 1-4 MPa. High energy consumption caused by high-temperature and high-pressure dissolution, high concentration of dissolved alkali, high equipment requirement and long dissolution time. In order to ensure the utilization rate of equipment, the dissolution rate of alumina can only be sacrificed, and the dissolution rate of the alumina is less than 80 percent at present. It is also clear that the bauxite sintered by adding alkali and increasing calcium can reach the dissolution rate of 96% of alumina and alkali at normal pressure, 95 ℃, low concentration of dissolved alkali and shorter dissolution time, but the sintering is finished by using a rotary kiln at present, so that the investment of a sintering workshop is 1/3 of the whole plant, the sintering cost is about 1/2 of the cost, and the energy consumption is more than 50% of the total energy consumption of the whole plant. The main reasons for its high energy consumption are: 1. the raw materials are wet-milled into slurry, the particle fineness requires no more than 16 percent on a 170-mesh sieve, and high power consumption is needed for high-fineness milling; 2. the slurry carries in water to evaporate and consume heat, which accounts for 30 to 44 percent of the total heat consumption of the clinker kiln; 3. the waste gas carries out heat consumption accounting for 13-30%; 4. clinker carry-out and heat dissipation account for 20-28%. The main reasons for the high investment are the complexity and bulkiness of the rotary kiln, the low volume heat load, the evaporation and the burning time are very long, the length of the rotary kiln is at least 70 meters, even more than 200 meters, and the large smoke residual heat recovery equipment is also bulky. The evaporation and the burning time of the wet slurry are long, which are determined by the reaction process in the rotary kiln in the form of inter-particle solid-solid reaction, the inter-particle solid-solid reaction depends on the fineness and uniform mixing of particles, the reaction temperature is effectively improved, but after lime and some components in bauxite are added to react with alkali, the melting point is obviously reduced, and the temperature in the kiln is limited to be increased. On the other hand, under the condition that the environmental standard is more and more strict, the kiln temperature of the existing rotary kiln sintering method is about 1250 ℃, a large amount of nitrogen oxides can be generated, and the rotary kiln sintering method is difficult to exist.

Both the bayer process and the rotary kiln sintering process produce a large amount of red mud, which is currently discarded, causing serious pollution. At present, some enterprises mix red mud and bauxite, increase calcium and then sinter the mixture in a rotary kiln to recover alkali and aluminum in the red mud. Because the red mud contains compounds of alkali and titanium oxide, the melting point of the red mud is only about 1100 ℃, and the doping amount of the red mud is obviously limited. The drawbacks of the rotary kiln sintering described above still exist. The method reduces the energy consumption, investment and cost of the sintering method, particularly the emission of nitrogen oxides, simultaneously reserves the advantages of simple dissolving-out equipment and low energy consumption, and is an important subject of the alumina production in China.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, the invention aims to provide a liquid state fusion sintering-cold quenching method for adding alkali and increasing calcium to a lean iron high-aluminum material, which adopts the fusion sintering and cold quenching processes to treat the lean iron high-aluminum material, and can reduce energy consumption and improve the aluminum recovery rate while avoiding wet grinding and fine granularity and shortening the reaction time.

In one aspect of the invention, the invention provides a liquid-state fusion sintering-cold quenching method for adding alkali and calcium to a lean iron and high aluminum material. According to an embodiment of the invention, the method comprises:

(1) mixing the lean iron and high aluminum material with alkali and limestone to perform melting sintering so as to obtain a molten liquid material;

(2) performing cold quenching on the molten liquid material to obtain solid particles;

(3) and (3) grinding the solid particles, and then dissolving out dilute alkali to obtain calcium-rich tail powder and a solution containing sodium aluminate.

According to the liquid melt sintering-cold quenching method for adding alkali to increase calcium for the iron-poor high-aluminum material, because the melting point of the eutectic of titanium oxide and alkali in the iron-poor high-aluminum material is the lowest, once the eutectic of titanium oxide and alkali begins to melt, the eutectic phenomenon can be generated, namely the melting points of other components are reduced, so that the reaction of the iron-poor high-aluminum material and limestone is carried out in a melt liquid environment, the reaction process is liquid-liquid contact, when the material is converted into a melt liquid state, even if the original particles are thick, the particles can be quickly fused, the reaction time can be shortened by more than 10 times compared with the reaction time in a conventional rotary kiln, then the obtained melt liquid material is subjected to cold quenching, each component is not ready to crystallize, so that solid particles with high reaction activity can be obtained, finally, the obtained solid particles are ground and diluted alkali is dissolved, and many reactions are quickly completed during dissolution, separating to obtain the calcium-rich tail powder and the solution containing sodium aluminate. Therefore, the method adopts the melting sintering and cold quenching processes to treat the lean iron and high aluminum material, and can reduce energy consumption and improve the aluminum recovery rate while avoiding wet grinding and fine granularity and shortening reaction time. Specifically, the aluminum recovery rate can reach more than 96% by adopting the method.

In addition, the liquid-state melt sintering-cold quenching method for adding alkali and calcium to the iron-poor high-alumina material according to the embodiment of the invention can also have the following additional technical characteristics:

in some embodiments of the invention, in step (1), the iron content of the iron-depleted high alumina material is not higher than 7 mass%, and the alumina content is not lower than 20 mass%.

In some embodiments of the invention, in the step (1), the iron-poor high-alumina material is a residual material of bauxite after recovering 10-30 mass% of ferric oxide in the total amount, or a residual material of a mixed material including red mud and bauxite after recovering 20-50 mass% of ferric oxide in the total amount.

In some embodiments of the present invention, in the step (1), the red mud in the mixed material comprising red mud and bauxite accounts for 10 to 70% of the total weight of the mixed material, preferably 40 to 60%.

In some embodiments of the invention, in the step (1), the alkali comprises sodium hydroxide and/or sodium carbonate, and the addition amount of the alkali is (0.8-1.2) in terms of the molar ratio of the content of sodium oxide to the content of aluminum oxide in the iron-depleted high-alumina material: 1, preferably (0.9-1): 1. thus, energy consumption can be reduced and the aluminum recovery rate can be improved.

In some embodiments of the invention, in the step (1), the limestone is added in an amount of 2 to 2.8 times the equivalent of the sum of silica and titania in the iron-deficient high-alumina material. Thus, energy consumption can be reduced and the aluminum recovery rate can be improved.

In some embodiments of the present invention, in step (1), the melt sintering apparatus is a melt furnace. Thus, the aluminum recovery rate can be improved while the investment and running costs are reduced.

In some embodiments of the present invention, in the step (1), the melting and sintering temperature is 1150 to 1400 ℃. Thus, energy consumption can be reduced and the aluminum recovery rate can be improved.

In some embodiments of the invention, in step (2), the cold quench rate is not less than 500 ℃/s. Thus, energy consumption can be reduced and the aluminum recovery rate can be improved.

In some embodiments of the invention, in step (2), the solid particles have a particle size of no greater than 5 mm. Thus, energy consumption can be reduced and the aluminum recovery rate can be improved.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic flow diagram of a liquid-state fusion sintering-cold quenching method for adding alkali and calcium to an iron-poor high-alumina material according to an embodiment of the invention.

Detailed Description

The following detailed description of the embodiments of the present invention is intended to be illustrative, and not to be construed as limiting the invention.

In one aspect of the invention, the invention provides a liquid-state fusion sintering-cold quenching method for adding alkali and calcium to a lean iron and high aluminum material. According to an embodiment of the invention, with reference to fig. 1, the method comprises:

s100: mixing the lean iron and high aluminum material with alkali and limestone for melting and sintering

In this step, the iron-poor high-alumina material may be defined as "any material having an iron content of not higher than 7% by mass and an aluminum oxide content of not lower than 20% by mass and including titanium oxide, etc.," for example, the iron-poor high-alumina material is a residual material obtained by recovering 10 to 30% by mass of ferric oxide from bauxite or a residual material obtained by recovering 20 to 50% by mass of ferric oxide from a mixed material including red mud and bauxite, and is melt-sintered by mixing the iron-poor high-alumina material with alkali and limestone, since the melting point of a eutectic of titanium oxide and alkali in the iron-poor high-alumina material is the lowest, once the eutectic of titanium oxide and alkali begins to melt, a eutectic phenomenon will occur, i.e., the melting points of other components will be lowered, so that the reaction of the iron-poor high-alumina material with limestone will proceed in a molten liquid environment, the reaction process is liquid-liquid contact, when the material is converted into a molten liquid state, even if the original particles are thick, the material can still be quickly fused, and the reaction time can be shortened by more than 10 times compared with the reaction time in a conventional rotary kiln.

Further, the alkali comprises sodium hydroxide and/or sodium carbonate, and the addition amount of the alkali is (0.8-1.2) in terms of the molar ratio of the content of sodium oxide to the content of aluminum oxide in the iron-poor high-alumina material: 1, preferably (0.9-1): 1, and the addition amount of limestone is 2-2.8 times of the sum equivalent of silicon dioxide and titanium dioxide in the lean iron high-aluminum material. Meanwhile, when the lean iron and high aluminum material is a mixed material comprising red mud and bauxite, the red mud in the mixed material accounts for 10-70% of the total weight of the mixed material, and preferably 40-60%. Therefore, the resource utilization of the red mud and the bauxite can be realized simultaneously.

Furthermore, the above-mentioned equipment for mixing the iron-poor high-alumina material with alkali and limestone to perform the melting sintering reaction includes but is not limited to a melting furnace, as long as the requirement of mixing the iron-poor high-alumina material with alkali and limestone to perform the melting sintering can be met, compared with the conventional technology in which a rotary kiln is used for sintering, the wet material is firstly converted into the dry material, so that the preheating evaporation time is saved, and the energy consumption is reduced; and secondly, the components are easy to mix after being melted into liquid state, so that the reaction time is obviously shortened, the volume of equipment is reduced by more than 10 times, and the particle size of the particles entering the furnace can be enlarged by more than 5 times. The melting and sintering equipment can ensure that the lean iron and high aluminum material, alkali and limestone are completely melted. Meanwhile, the melting and sintering temperature is 1150-1400 ℃, preferably 1200-1300 ℃, and the materials are in good liquid state under the temperature condition, so that the reaction rate is improved.

S200: cold quenching the molten liquid material

In the step, the obtained molten liquid material is subjected to cold quenching, and all components are not in time to crystallize, so that solid particles with high reaction activity can be obtained, and the subsequent aluminum recovery rate is improved. Further, the cold quenching rate is not lower than 500 ℃/s, namely the molten liquid material obtained in the melting and sintering process is discharged from the melting and sintering equipment and then is rapidly cold quenched, so that the temperature of the molten liquid material is reduced from more than 1100 ℃ to less than 200 ℃ within 2 seconds, and solid particles with the particle size of not more than 5mm are obtained. It should be noted that the manner of quenching in this step is not particularly limited as long as rapid quenching of the molten liquid material can be achieved.

S300: grinding the solid particles and then carrying out dilute alkali dissolution

In the step, the obtained solid particles are ground and then diluted alkali is dissolved out, and then solid-liquid separation is carried out to obtain calcium-rich tail powder and a solution containing sodium aluminate. It should be noted that the particle size of the ground solid particles and the dilute alkali are not particularly limited as long as the recovery rate of alumina can be improved.

According to the liquid melt sintering-cold quenching method for adding alkali to increase calcium for the iron-poor high-aluminum material, the melting point of the eutectic of titanium oxide and alkali in the iron-poor high-aluminum material is the lowest, so that the eutectic phenomenon can be generated once the eutectic of titanium oxide and alkali begins to melt, namely the melting point of other components is reduced, so that the reaction of the iron-poor high-aluminum material and limestone is carried out in a molten liquid environment, the reaction process is liquid-liquid contact, when the material is converted into the molten liquid state, even if the original particles are thick, the particles can be rapidly fused, compared with a rotary kiln sintering method, as the wet material is converted into the dry material, the evaporation heat and the evaporation time which account for 40 percent of the original heat consumption are saved, and meanwhile, as the particle fineness and the long reaction time are not needed to achieve better reaction rate, only the melting into the liquid state is required, the particle size of the material can be properly increased, the volume of a combustion chamber is reduced by more, the grinding power consumption is reduced by more than 5 times, the heat dissipation loss of sintering equipment is reduced by more than 80%, the investment amount of the sintering equipment can be reduced by more than 5 times, the reaction time can be shortened by more than 10 times, then the obtained molten liquid material is subjected to cold quenching, all components are not in time to crystallize, so that solid particles with high reaction activity can be obtained, finally the obtained solid particles are ground and then diluted alkali is dissolved out, many reactions are quickly completed during dissolution, and the calcium-rich tail powder and the solution containing sodium aluminate can be obtained by separation. Therefore, the method adopts the melting sintering and cold quenching processes to treat the lean iron and high aluminum material, and can reduce energy consumption and improve the aluminum recovery rate while avoiding wet grinding and fine granularity and shortening reaction time. Specifically, the aluminum recovery rate can reach more than 96% by adopting the method.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.