Method for preparing pseudo-boehmite from aluminum ash

Abstract

The invention relates to a method for preparing pseudo-boehmite from aluminum ash, which comprises the following steps: mixing the aluminum ash and an alkaline solution for leaching to obtain a sodium aluminate leaching solution and alkaline leaching residues, and neutralizing the sodium aluminate leaching solution by using an acidic solution to obtain the pseudo-boehmite. According to the method, the aluminum ash is used as a raw material, a sodium aluminate solution is obtained through leaching of an alkaline solution, the concentration of hydroxyl radicals in the sodium aluminate solution is high, then the sodium aluminate solution and an acid solution are subjected to a neutralization reaction, and the pore volume of the pseudo-boehmite is increased by utilizing the property that the viscosity of the pseudo-boehmite is increased in an acid environment and utilizing pH swing in the neutralization process. The prepared pseudo-boehmite is high in specific surface area and large in pore volume, and can be widely applied to industrial production. The method provided by the invention is beneficial to realizing high-value utilization of aluminum resources in the aluminum ash, and can solve the problems that the aluminum ash is difficult to dispose and the resources are seriously wasted at present.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum ash recycling and utilization, and relates to a method for preparing pseudo-boehmite, and in particular to a method for preparing pseudo-boehmite from aluminum ash. Background Art

[0002] Aluminum ash is an intermediate product in the aluminum smelting industry. In addition to aluminum and aluminum oxide, it also contains easily hydrolyzed aluminum nitride and heavy metals such as lead and cadmium. Therefore, the resource utilization and harmless disposal of aluminum ash has become a problem that needs to be solved urgently.

[0003] At present, the recovery of aluminum in aluminum ash is mainly divided into two paths. One is the resource recovery process, which mainly recycles aluminum and other resources through pyrometallurgical extraction. For example, ash roasting recovery method, rotary kiln recovery method and pressing recovery method. The other is to use aluminum ash to prepare various materials with application value, such as aluminum sulfate, polyaluminum sulfate, polyaluminum chloride, calcium aluminate and other aluminum products. However, the added value of the product is not high. Therefore, it is urgent to develop a harmless and high-value treatment method for aluminum ash. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for preparing pseudo-boehmite from aluminum ash. The present invention uses aluminum ash as a raw material, firstly obtains a sodium aluminate solution by leaching with an alkaline solution, and the sodium aluminate solution has a high hydroxide concentration, and then undergoes a neutralization reaction with an acidic solution, utilizing the property of pseudo-boehmite that the viscosity increases in an acidic environment, and utilizing pH swing during the neutralization process to increase the pore volume of the pseudo-boehmite. The pseudo-boehmite prepared by the present invention has a high specific surface area and a large pore volume, and can be widely used in industrial production. The method provided by the present invention is conducive to realizing the high-value utilization of aluminum resources in aluminum ash, and can solve the current problems of difficult aluminum ash disposal and serious waste of resources.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing pseudo-boehmite from aluminum ash, the method comprising the following steps:

[0007] Aluminum ash and alkaline solution are mixed for leaching to obtain sodium aluminate leaching solution and alkaline leaching residue, and the sodium aluminate leaching solution is neutralized with an acidic solution to obtain the pseudo-boehmite.

[0008] The present invention uses aluminum ash as a raw material, firstly obtains a sodium aluminate solution by leaching with an alkaline solution, and the sodium aluminate solution has a high hydroxide concentration, and then undergoes a neutralization reaction with an acidic solution, utilizing the property of pseudo-boehmite that the viscosity increases in an acidic environment, and utilizing pH swing during the neutralization process to increase the pore volume of the pseudo-boehmite. The pseudo-boehmite prepared by the present invention has a high specific surface area and a large pore volume, and can be widely used in industrial production. The method provided by the present invention is conducive to realizing the high-value utilization of aluminum resources in aluminum ash, and can solve the current problems of difficult aluminum ash disposal and serious waste of resources.

[0009] Preferably, the alkaline solution comprises any one or a combination of at least two of sodium hydroxide, potassium hydroxide or ammonia water. Typical but non-limiting combinations include a combination of sodium hydroxide and potassium hydroxide, or a combination of sodium hydroxide, potassium hydroxide and ammonia water, preferably sodium hydroxide.

[0010] Preferably, the alkaline solution has a concentration of 100 g / L-500 g / L, for example, 50 g / L, 100 g / L, 200 g / L, 300 g / L, 400 g / L or 500 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 100 g / L-200 g / L.

[0011] Preferably, the liquid-to-solid ratio of the leaching is 1 mL / g-50 mL / g, for example, it can be 1 mL / g, 5 mL / g, 10 mL / g, 20 mL / g, 30 mL / g, 40 mL / g or 50 mL / g, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 5 mL / g-10 mL / g.

[0012] Preferably, the leaching insulation temperature is 20°C-100°C, for example, it can be 20°C, 30°C, 50°C, 70°C, 80°C, 90°C or 100°C, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 30°C-90°C.

[0013] Preferably, the leaching holding time is 0.5h-10h, for example, it can be 0.5h, 1h, 3h, 5h, 7h, 9h or 10h, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 1h-6h.

[0014] The present invention can further improve the leaching effect by further regulating the liquid-to-solid ratio of leaching, the leaching insulation temperature and the leaching insulation time. Under the preferred liquid-to-solid ratio, insulation temperature and insulation time, the alkali leaching rate of aluminum ash is further improved, which is conducive to further improving the total leaching rate of aluminum in the aluminum ash.

[0015] Preferably, the mixing method comprises a first stirring.

[0016] Preferably, the first stirring rotation speed is 50r / min-500r / min, for example, it can be 50r / min, 100r / min, 200r / min, 300r / min, 400r / min or 500r / min, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 100r / min-400r / min.

[0017] Preferably, the acidic solution comprises any one of sulfuric acid, hydrochloric acid or nitric acid or a combination of at least two thereof, and a typical but non-limiting combination comprises a combination of sulfuric acid and hydrochloric acid, or a combination of sulfuric acid, hydrochloric acid and nitric acid, preferably sulfuric acid.

[0018] Preferably, the concentration of the acidic solution is 0.1mol / L-18mol / L, for example, it can be 0.1mol / L, 0.5mol / L, 1mol / L, 3mol / L, 5mol / L, 10mol / L, 15mol / L or 18mol / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 0.5mol / L-5mol / L.

[0019] Preferably, the acid solution is added at a rate of 10 ml / min-500 ml / min, for example, 10 ml / min, 100 ml / min, 200 ml / min, 300 ml / min, 400 ml / min or 500 ml / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable, preferably 20 ml / min-100 ml / min.

[0020] Preferably, the pH value of the neutralization is 2-10, for example, 2, 3, 5, 7, 9 or 10, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, preferably 5-9.

[0021] Preferably, the neutralization insulation temperature is 10°C-100°C, for example, it can be 10°C, 20°C, 50°C, 70°C, 80°C, 90°C or 100°C, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 20°C-90°C.

[0022] Preferably, the neutralization insulation time is 0.1h-10h, for example, it can be 0.1h, 0.5h, 1h, 3h, 5h, 7h, 9h or 10h, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 1h-5h.

[0023] The present invention can further regulate the purity and crystallinity of the pseudo-boehmite by further regulating the neutralization pH value, the neutralization insulation temperature and the insulation time. Under the preferred pH value, insulation temperature and insulation time, the prepared pseudo-boehmite has a further improved purity, and a further improved specific surface area and pore volume.

[0024] Preferably, a second stirring is performed during the neutralization process.

[0025] Preferably, the rotation speed of the second stirring is 50r / min-500r / min, for example, it can be 50r / min, 100r / min, 200r / min, 300r / min, 400r / min or 500r / min, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 100r / min-400r / min.

[0026] Preferably, the method further comprises the following steps: after acid leaching the alkaline leaching residue, adding the sodium aluminate leaching solution to carry out polymerization reaction to obtain polyaluminium chloride.

[0027] In order to improve the recovery rate of aluminum, the present invention also recycles the alkali leaching residue. The sodium aluminate obtained in the previous stage is used to carry out polymerization reaction with the alkali leaching residue after acid leaching to obtain polyaluminum chloride. This process can further reduce the alkali leaching residue, convert the alkali leaching residue into polyaluminum chloride, realize further recovery of aluminum, and thus improve the recovery rate of aluminum.

[0028] Preferably, the leaching agent for acid leaching includes any one of sulfuric acid, hydrochloric acid or nitric acid, or a combination of at least two of them. Typical but non-limiting combinations include a combination of sulfuric acid and hydrochloric acid, or a combination of sulfuric acid, hydrochloric acid and nitric acid, preferably hydrochloric acid.

[0029] Preferably, the solution concentration of the leaching agent is 0.1mol / L-10mol / L, for example, it can be 0.1mol / L, 1mol / L, 2mol / L, 5mol / L, 8mol / L, 9mol / L or 10mol / L, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 2mol / L-8mol / L.

[0030] Preferably, the liquid-to-solid ratio of the acid leaching is 1 mL / g-50 mL / g, for example, 1 mL / g, 5 mL / g, 10 mL / g, 20 mL / g, 30 mL / g, 40 mL / g or 50 mL / g, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable, preferably 5 mL / g-10 mL / g.

[0031] Preferably, the holding temperature of the acid leaching is 20°C-100°C, for example, it can be 20°C, 30°C, 50°C, 70°C, 80°C, 90°C or 100°C, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 30°C-90°C.

[0032] Preferably, the holding time of the acid leaching is 0.5h-10h, for example, it can be 0.5h, 1h, 3h, 5h, 7h, 9h or 10h, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 1h-6h.

[0033] The present invention can further improve the leaching effect by further regulating the acid leaching liquid-solid ratio, acid leaching insulation temperature and acid leaching insulation time. At the preferred acid leaching liquid-solid ratio, acid leaching insulation temperature and acid leaching insulation time, the acid leaching rate of the alkali leaching residue is further improved, which is conducive to further improving the total leaching rate of aluminum in aluminum ash.

[0034] Preferably, a third stirring is performed during the acid leaching process.

[0035] Preferably, the third stirring speed is 50r / min-500r / min, for example, it can be 50r / min, 100r / min, 200r / min, 300r / min, 400r / min or 500r / min, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 100r / min-400r / min.

[0036] Preferably, the pH value of the polymerization reaction is 0.5-6, for example, 0.5, 1, 2, 3, 5 or 6, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable, preferably 2-4.

[0037] Preferably, the insulation temperature of the polymerization reaction is 20°C-100°C, for example, it can be 20°C, 30°C, 50°C, 70°C, 80°C, 90°C or 100°C, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 30°C-90°C.

[0038] Preferably, the insulation time of the polymerization reaction is 0.1h-10h, for example, it can be 0.1h, 0.5h, 1h, 3h, 5h, 7h, 9h or 10h, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 1h-6h.

[0039] The present invention can further improve the yield of polyaluminium chloride by further regulating the pH value of the polymerization reaction, the insulation temperature of the polymerization reaction and the insulation time of the polymerization reaction. Under the preferred polymerization reaction pH value, the insulation temperature of the polymerization reaction and the insulation time of the polymerization reaction, the prepared polyaluminium chloride has a high degree of polymerization and a high yield.

[0040] Preferably, a fourth stirring step is performed during the polymerization reaction.

[0041] Preferably, the fourth stirring speed is 50r / min-500r / min, for example, it can be 50r / min, 100r / min, 200r / min, 300r / min, 400r / min or 500r / min, but is not limited to the listed values. Other unlisted values ​​within the numerical range are also applicable, preferably 100r / min-400r / min.

[0042] As a preferred technical solution of the present invention, the method comprises the following steps:

[0043] (1) mixing aluminum ash and alkaline solution at a liquid-to-solid ratio of 1 mL / g-50 mL / g, leaching at 20° C.-100° C. for 0.5 h-10 h to obtain sodium aluminate leaching solution and alkaline leaching residue;

[0044] (2) adding an acidic solution to the sodium aluminate leachate of step (1) at a rate of 10 ml / min-500 ml / min, and performing a neutralization reaction at a pH of 2-10 to obtain the pseudo-boehmite, wherein the neutralization reaction is held at a temperature of 10° C.-100° C. and a neutralization holding time of 0.1 h-10 h;

[0045] (3) mixing the acid leaching agent and the alkaline leaching residue at a liquid-solid ratio of 1 mL / g-50 mL / g, and after acid leaching at 20° C.-100° C. for 0.5 h-10 h, adding part of the sodium aluminate leaching solution of step (1) to carry out polymerization reaction to obtain polyaluminum chloride, wherein the pH value of the polymerization reaction is 0.5-6, the insulation temperature of the polymerization reaction is 20° C.-100° C., and the insulation time of the polymerization reaction is 0.1 h-10 h;

[0046] Among them, step (2) and step (3) are performed in no particular order.

[0047] Compared with the prior art, the present invention has at least the following beneficial effects:

[0048] (1) The present invention uses aluminum ash as a raw material, firstly leaches it in an alkaline solution at normal pressure to obtain a sodium aluminate solution, wherein the sodium aluminate solution has a high hydroxide concentration, and then neutralizes it with an acidic solution, utilizing the property that the viscosity of pseudo-boehmite increases in an acidic environment, and utilizing pH swing during the neutralization process to increase the pore volume of the pseudo-boehmite.

[0049] (2) The pseudo-boehmite prepared by the present invention has a high specific surface area and a large pore volume, and can be widely used in industrial production; further, the polyaluminium chloride product prepared by the present invention also has a broad application prospect, and realizes the high-value utilization of aluminium ash.

[0050] (3) The method provided by the present invention is conducive to realizing the high-value utilization of aluminum resources in aluminum ash, and can solve the current problems of difficult aluminum ash disposal and serious waste of resources. At the same time, the method of the present invention not only has mild conditions, but also does not require high temperature and pressurization, and has the advantages of simple process and low production cost.

[0051] (4) The present invention can achieve a total leaching rate of aluminum in aluminum ash as high as 58.8% or more, thereby realizing the resource utilization and reduction of aluminum ash. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 The present invention is a process flow chart of preparing pseudo-boehmite by using aluminum ash. DETAILED DESCRIPTION

[0053] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0054] Example 1

[0055] This embodiment provides a method for preparing pseudo-boehmite from aluminum ash, the method comprising the following steps:

[0056] (1) mixing aluminum ash and 100 g / L sodium hydroxide solution at a liquid-to-solid ratio of 8 mL / g, leaching at 80° C. for 4 h, with a first stirring during the leaching process to obtain a sodium aluminate leachate and an alkaline leaching residue, wherein the rotation speed of the first stirring is 200 r / min;

[0057] (2) adding 1 mol / L sulfuric acid solution to the sodium aluminate leachate of step (1) at a rate of 50 ml / min, and conducting a neutralization reaction at a pH of 7, accompanied by a second stirring during the neutralization reaction, to obtain the pseudo-boehmite, wherein the insulation temperature of the neutralization reaction is 80° C., the insulation time of the neutralization is 2 h, and the speed of the second stirring is 200 r / min;

[0058] (3) mixing 6 mol / L hydrochloric acid and the alkaline leached residue at a liquid-solid ratio of 5 mL / g, acid leaching at 80° C. for 4 h, with a third stirring during the acid leaching process, adding part of the sodium aluminate leaching solution of step (1) to carry out a polymerization reaction, with a fourth stirring during the polymerization reaction, to obtain polyaluminium chloride, wherein the pH value of the polymerization reaction is 3, the insulation temperature of the polymerization reaction is 80° C., the insulation time of the polymerization reaction is 3 h, the rotation speed of the third stirring is 200 r / min, and the rotation speed of the fourth stirring is 200 r / min;

[0059] Among them, step (2) and step (3) are performed in no particular order.

[0060] Example 2

[0061] This embodiment provides a method for preparing pseudo-boehmite from aluminum ash, the method comprising the following steps:

[0062] (1) mixing aluminum ash and 100 g / L potassium hydroxide solution at a liquid-solid ratio of 5 mL / g, leaching at 90° C. for 1 h, with a first stirring during the leaching process to obtain a sodium aluminate leaching solution and an alkaline leaching residue, wherein the rotation speed of the first stirring is 100 r / min;

[0063] (2) adding 0.1 mol / L nitric acid solution to the potassium aluminate leachate of step (1) at a rate of 10 ml / min, and conducting a neutralization reaction at a pH of 9, accompanied by a second stirring during the neutralization reaction, to obtain the pseudo-boehmite, wherein the insulation temperature of the neutralization reaction is 90° C., the insulation time of the neutralization is 1 h, and the speed of the second stirring is 100 r / min;

[0064] (3) mixing 8 mol / L nitric acid and the alkaline leached residue at a liquid-solid ratio of 5 mL / g, acid leaching at 90° C. for 1 h, with a third stirring during the acid leaching process, adding part of the potassium aluminate leaching solution of step (1) to carry out a polymerization reaction, with a fourth stirring during the polymerization reaction, to obtain polyaluminium chloride, wherein the pH value of the polymerization reaction is 2, the insulation temperature of the polymerization reaction is 90° C., the insulation time of the polymerization reaction is 1 h, the rotation speed of the third stirring is 100 r / min, and the rotation speed of the fourth stirring is 100 r / min;

[0065] Among them, step (2) and step (3) are performed in no particular order.

[0066] Example 3

[0067] This embodiment provides a method for preparing pseudo-boehmite from aluminum ash, the method comprising the following steps:

[0068] (1) mixing aluminum ash and 500 g / L sodium hydroxide solution at a liquid-to-solid ratio of 10 mL / g, leaching at 30° C. for 6 h, with a first stirring during the leaching process to obtain a sodium aluminate leaching solution and an alkaline leaching residue, wherein the rotation speed of the first stirring is 400 r / min;

[0069] (2) adding 18 mol / L hydrochloric acid solution to the sodium aluminate leachate of step (1) at a rate of 500 ml / min, and conducting a neutralization reaction at a pH of 5, accompanied by a second stirring during the neutralization reaction, to obtain the pseudo-boehmite, wherein the insulation temperature of the neutralization reaction is 20° C., the insulation time of the neutralization is 5 h, and the speed of the second stirring is 400 r / min;

[0070] (3) mixing 2 mol / L hydrochloric acid and the alkaline leached residue at a liquid-solid ratio of 10 mL / g, acid leaching at 30° C. for 6 h, with a third stirring during the acid leaching process, adding part of the sodium aluminate leaching solution of step (1) to carry out a polymerization reaction, with a fourth stirring during the polymerization reaction, to obtain polyaluminium chloride, wherein the pH value of the polymerization reaction is 4, the insulation temperature of the polymerization reaction is 30° C., the insulation time of the polymerization reaction is 6 h, the rotation speed of the third stirring is 400 r / min, and the rotation speed of the fourth stirring is 400 r / min;

[0071] Among them, step (2) and step (3) are performed in no particular order.

[0072] Example 4

[0073] The only difference between this embodiment and embodiment 1 is that, except that the leaching temperature in step (1) is 20° C., the rest is the same as embodiment 1.

[0074] Example 5

[0075] The only difference between this embodiment and embodiment 1 is that, except that the leaching temperature in step (1) is 100° C., the rest is the same as embodiment 1.

[0076] Example 6

[0077] The only difference between this embodiment and embodiment 1 is that, except that the leaching time in step (1) is 0.5 h, the rest is the same as embodiment 1.

[0078] Example 7

[0079] The only difference between this embodiment and embodiment 1 is that, except that the leaching time in step (1) is 10 h, the rest is the same as embodiment 1.

[0080] Example 8

[0081] The only difference between this embodiment and embodiment 1 is that, except that the liquid-to-solid ratio of the alkaline leaching in step (1) is 1 mL / g, the rest is the same as embodiment 1.

[0082] Example 9

[0083] The only difference between this embodiment and embodiment 1 is that, except that the liquid-to-solid ratio of the alkaline leaching in step (1) is 50 mL / g, the rest is the same as embodiment 1.

[0084] Example 10

[0085] The only difference between this embodiment and embodiment 1 is that, except that the insulation temperature of the neutralization reaction in step (2) is 10° C., the rest is the same as embodiment 1.

[0086] Embodiment 11

[0087] The only difference between this embodiment and embodiment 1 is that, except that the insulation temperature of the neutralization reaction in step (2) is 100° C., the rest is the same as embodiment 1.

[0088] Example 12

[0089] The only difference between this embodiment and embodiment 1 is that, except that the pH value of the neutralization reaction in step (2) is 2, the rest is the same as embodiment 1.

[0090] Embodiment 13

[0091] The only difference between this embodiment and embodiment 1 is that, except that the pH value of the neutralization reaction in step (2) is 10, the rest is the same as embodiment 1.

[0092] Embodiment 14

[0093] The only difference between this embodiment and embodiment 1 is that, except that the holding time of the neutralization reaction in step (2) is 0.1 h, the rest is the same as embodiment 1.

[0094] Embodiment 15

[0095] The only difference between this embodiment and embodiment 1 is that, except that the holding time of the neutralization reaction in step (2) is 10 h, the rest is the same as embodiment 1.

[0096] Example 16

[0097] The only difference between this embodiment and embodiment 1 is that, except that the holding temperature of the acid leaching in step (3) is 20° C., the rest is the same as embodiment 1.

[0098] Embodiment 17

[0099] The only difference between this embodiment and embodiment 1 is that, except that the holding temperature of the acid leaching in step (3) is 100° C., the rest is the same as embodiment 1.

[0100] Embodiment 18

[0101] The only difference between this embodiment and embodiment 1 is that, except that the concentration of hydrochloric acid in step (3) is 0.1 mol / L, the rest is the same as embodiment 1.

[0102] Embodiment 19

[0103] The only difference between this embodiment and embodiment 1 is that, except that the concentration of hydrochloric acid in step (3) is 10 mol / L, the rest is the same as embodiment 1.

[0104] Embodiment 20

[0105] The only difference between this embodiment and embodiment 1 is that, except that the holding time of the acid leaching in step (3) is 0.5 h, the rest is the same as embodiment 1.

[0106] Embodiment 21

[0107] The only difference between this embodiment and embodiment 1 is that, except that the holding time of the acid leaching in step (3) is 10 hours, the rest is the same as embodiment 1.

[0108] Embodiment 22

[0109] The only difference between this embodiment and embodiment 1 is that, except that the liquid-to-solid ratio of the acid leaching in step (3) is 1 mL / g, the rest is the same as embodiment 1.

[0110] Embodiment 23

[0111] The only difference between this embodiment and embodiment 1 is that, except that the liquid-to-solid ratio of the acid leaching in step (3) is 50 mL / g, the rest is the same as embodiment 1.

[0112] Embodiment 24

[0113] The only difference between this embodiment and embodiment 1 is that, except that the pH value of the polymerization reaction in step (3) is 0.5, the rest is the same as embodiment 1.

[0114] Embodiment 25

[0115] The only difference between this embodiment and embodiment 1 is that, except that the pH value of the polymerization reaction in step (3) is 6, the rest is the same as embodiment 1.

[0116] Embodiment 26

[0117] The only difference between this embodiment and embodiment 1 is that, except that the insulation temperature of the polymerization reaction in step (3) is 20° C., the rest is the same as embodiment 1.

[0118] Embodiment 27

[0119] The only difference between this embodiment and embodiment 1 is that, except that the holding temperature of the polymerization reaction in step (3) is 100° C., the rest is the same as embodiment 1.

[0120] Embodiment 28

[0121] The only difference between this embodiment and embodiment 1 is that, except that the holding time of the polymerization reaction in step (3) is 0.1 h, the rest is the same as embodiment 1.

[0122] Embodiment 29

[0123] The only difference between this embodiment and embodiment 1 is that, except that the holding time of the polymerization reaction in step (3) is 10 h, the rest is the same as embodiment 1.

[0124] Comparative Example 1

[0125] This comparative example provides a method for preparing pseudo-boehmite from aluminum ash, the method comprising the following steps:

[0126] (1) mixing aluminum ash and 1 mol / L sulfuric acid solution at a liquid-to-solid ratio of 8 g / mL, leaching at 80° C. for 4 h, accompanied by a first stirring during the leaching process, to obtain a sodium aluminate leaching solution and acid leaching residue, wherein the rotation speed of the first stirring is 200 r / min;

[0127] (2) adding 100 g / L sodium hydroxide solution to the sodium aluminate leachate of step (1) at a rate of 50 ml / min, and conducting a neutralization reaction at a pH of 7, accompanied by a second stirring during the neutralization reaction, to obtain the pseudo-boehmite, wherein the insulation temperature of the neutralization reaction is 80° C., the insulation time of the neutralization is 2 h, and the speed of the second stirring is 200 r / min;

[0128] (3) mixing 6 mol / L sodium hydroxide and the acid leaching residue at a liquid-solid ratio of 5 g / mL, alkali leaching at 80° C. for 4 h, with a third stirring during the alkali leaching, adding part of the sodium aluminate leaching solution of step (1) to carry out a polymerization reaction, with a fourth stirring during the polymerization reaction, to obtain polyaluminum chloride, wherein the pH value of the polymerization reaction is 3, the insulation temperature of the polymerization reaction is 80° C., the insulation time of the polymerization reaction is 3 h, the rotation speed of the third stirring is 200 r / min, and the rotation speed of the fourth stirring is 200 r / min;

[0129] Among them, step (2) and step (3) are performed in no particular order.

[0130] Test Method

[0131] The masses of pseudo-boehmite and polyaluminium chloride prepared in Examples 1 to 29 and Comparative Example 1 were measured, and the leaching rate of aluminium element was calculated and recorded in Table 1;

[0132] The specific surface area and pore volume of pseudo-boehmite were measured using the specific surface area tester ASAP 2020HD88 from Micromeritics Instruments, USA, and are recorded in Table 1;

[0133] The basicity of polyaluminium chloride is determined by chemical titration, the principle of which is to mix the sample with a certain amount of hydrochloric acid and consume the 3+ Bound OH - . After adding enough potassium fluoride solution, the Al 3+ Converted to AlF 3 Precipitation to remove Al 3+ Finally, the remaining hydrochloric acid is titrated with standard sodium hydroxide solution. At the same time, a blank test is performed with deionized water, and the volume V of the titration solution consumed when measuring the sample and the volume V of the titration solution consumed in the blank test are recorded. 0 (Calculation formula: basicity = (V 0 -V)×C×169.9 / (m×ω)×100%), V 0 —The volume of sodium hydroxide standard titration solution consumed in the blank test, V—the volume of sodium hydroxide standard titration solution consumed by the sample solution, C—the actual concentration of the sodium hydroxide standard titration solution, ω the alumina content of the sample, m-the mass of the sample, and record them in Table 1.

[0134] Table 1

[0135]

[0136]

[0137] The test results show that:

[0138] (1) It can be seen from Examples 1 to 29 and Comparative Example 1 that the present invention uses aluminum ash as a raw material, firstly obtains a sodium aluminate solution by leaching with an alkaline solution, and the sodium aluminate solution has a high hydroxide concentration, and then undergoes a neutralization reaction with an acidic solution, utilizing the property of pseudo-boehmite that the viscosity increases in an acidic environment, and utilizing pH swings during the neutralization process to increase the pore volume of the pseudo-boehmite. The pseudo-boehmite prepared by the present invention has a high specific surface area and a large pore volume, and can be widely used in industrial production. The method provided by the present invention is conducive to realizing the high-value utilization of aluminum resources in aluminum ash, and can solve the current problems of difficult aluminum ash disposal and serious waste of resources.

[0139] (2) It can be seen from Examples 1 and 4 to 9 that the present invention can further improve the leaching rate of aluminum element by further controlling the liquid-to-solid ratio, leaching temperature and leaching time of alkali leaching.

[0140] (3) It can be seen from Examples 1 and 10 to 15 that the specific surface area and pore volume of pseudo-boehmite can be further regulated by further controlling the pH value, insulation temperature and insulation time of the neutralization reaction.

[0141] (4) It can be seen from Example 1 and Example 16 to Example 23 that the present invention can further control the leaching rate of aluminum element by further controlling the liquid-to-solid ratio of acid leaching, the hydrochloric acid concentration, the holding temperature and the holding time of acid leaching.

[0142] (5) It can be seen from Example 1 and Example 24 to Example 29 that the polyaluminium chloride prepared in the present invention has a further reduced basicity by further controlling the pH value, the insulation temperature and the insulation time of the polymerization reaction.

[0143] In summary, the present invention uses aluminum ash as raw material, firstly obtains sodium aluminate solution by leaching with an alkaline solution, and the sodium aluminate solution has a high hydroxide concentration, and then undergoes a neutralization reaction with an acidic solution, utilizing the property of pseudo-boehmite that the viscosity increases in an acidic environment, and utilizing pH swings during the neutralization process to increase the pore volume of the pseudo-boehmite. The pseudo-boehmite prepared by the present invention has a high specific surface area and a large pore volume, and can be widely used in industrial production. The method provided by the present invention is conducive to realizing the high-value utilization of aluminum resources in aluminum ash, and can solve the current problems of difficult aluminum ash disposal and serious waste of resources.

[0144] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing pseudo-boehmite from aluminum ash, characterized in that: The method comprises the following steps: Aluminum ash and alkaline solution are mixed for leaching to obtain sodium aluminate leaching solution and alkaline leaching residue, and the sodium aluminate leaching solution is neutralized with an acidic solution to obtain the pseudo-boehmite.

2. The method according to claim 1, characterized in that: The alkaline solution comprises any one or a combination of at least two of sodium hydroxide, potassium hydroxide or ammonia water, preferably sodium hydroxide; Preferably, the alkaline solution has a concentration of 100 g / L-500 g / L, preferably 100 g / L-200 g / L.

3. The method according to claim 1 or 2, characterized in that: The liquid-to-solid ratio of the leaching is 1 mL / g-50 mL / g, preferably 5 mL / g-10 mL / g; Preferably, the leaching insulation temperature is 20°C-100°C, preferably 30°C-90°C; Preferably, the leaching insulation time is 0.5h-10h, preferably 1h-6h.

4. The method according to any one of claims 1 to 3, characterized in that: The mixing method includes first stirring; Preferably, the first stirring speed is 50 r / min-500 r / min, preferably 100 r / min-400 r / min.

5. The method according to any one of claims 1 to 4, characterized in that: The acidic solution comprises any one of sulfuric acid, hydrochloric acid or nitric acid or a combination of at least two thereof, preferably sulfuric acid; Preferably, the acid solution is added at a rate of 10 ml / min-500 ml / min, preferably 20 ml / min-100 ml / min.

6. The method according to any one of claims 1 to 5, characterized in that: The pH value of the neutralization is 2-10, preferably 5-9; Preferably, the neutralization insulation temperature is 10°C-100°C, preferably 20°C-90°C; Preferably, the neutralization insulation time is 0.1h-10h, preferably 1h-5h.

7. The method according to any one of claims 1 to 6, characterized in that: The method further comprises the steps of: After the alkaline leaching residue is acid leached, the sodium aluminate leaching solution is added to carry out polymerization reaction to obtain polyaluminium chloride.

8. The method according to claim 7, characterized in that The acid leaching agent includes any one of sulfuric acid, hydrochloric acid or nitric acid or a combination of at least two thereof, preferably hydrochloric acid; Preferably, the solution concentration of the leaching agent is 0.1mol / L-10mol / L, preferably 2mol / L-8mol / L; Preferably, the liquid-to-solid ratio of the acid leaching is 1 mL / g-50 mL / g, preferably 5 mL / g-10 mL / g; Preferably, the holding temperature of the acid leaching is 20°C-100°C, preferably 30°C-90°C; Preferably, the holding time of the acid leaching is 0.5h-10h, preferably 1h-6h.

9. The method according to claim 7 or 8, characterized in that: The pH value of the polymerization reaction is 0.5-6, preferably 2-4; Preferably, the polymerization reaction is held at a temperature of 20°C-100°C, preferably 30°C-90°C; Preferably, the insulation time of the polymerization reaction is 0.1h-10h, preferably 1h-6h.

10. The method according to claim 1, characterized in that The method comprises the following steps: (1) mixing aluminum ash and alkaline solution at a liquid-to-solid ratio of 1 mL / g to 50 mL / g, leaching at 20° C. to 100° C. for 0.5 h to 10 h to obtain sodium aluminate leaching solution and alkaline leaching residue; (2) adding an acidic solution to the sodium aluminate leachate of step (1) at a rate of 10 ml / min-500 ml / min, and performing a neutralization reaction at a pH of 2-10 to obtain the pseudo-boehmite, wherein the neutralization reaction is held at a temperature of 10° C.-100° C. and a neutralization holding time of 0.1 h-10 h; (3) mixing the acid leaching agent and the alkaline leaching residue at a liquid-solid ratio of 1 mL / g-50 mL / g, and after acid leaching at 20° C.-100° C. for 0.5 h-10 h, adding part of the sodium aluminate leaching solution of step (1) to carry out polymerization reaction to obtain polyaluminum chloride, wherein the pH value of the polymerization reaction is 0.5-6, the insulation temperature of the polymerization reaction is 20° C.-100° C., and the insulation time of the polymerization reaction is 0.1 h-10 h; Among them, step (2) and step (3) are performed in no particular order.

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