Ardealite activation method

Abstract

The invention provides an ardealite activation method which comprises the following steps: mixing ardealite with inorganic acid, reacting, performing solid-liquid separation, washing, and calcining, and cooling the calcined phosphogypsum, grinding, and adding an activation modifier to obtain the modified gypsum product. According to the method disclosed by the invention, the phosphogypsum is pretreated and calcined to fully remove impurities, and then is modified in a manner of grinding and adding an activating agent, so that the activation degree of the gypsum is improved, the oil absorption value is reduced, the utilization value of the gypsum is improved, the problem that the gypsum is limited in the aspect of filler application is solved, and the application field of the phosphogypsum is favorably expanded; the method is easy and convenient to operate, waste heat generated after calcination can be effectively utilized, heat in the system is fully utilized, the production cost is reduced, and the competitive advantage is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial solid waste utilization and relates to a method for activating phosphogypsum. Background Art

[0002] With the rapid development of industry, natural gypsum resources are mined and consumed, and a large amount of industrial by-product gypsum is also discharged. Industrial by-product gypsum refers to the by-product or waste residue with calcium sulfate as the main component generated by chemical reactions in industrial production. The most important type of industrial by-product gypsum is phosphogypsum. The discharge volume of phosphogypsum is large, and it has become the second largest solid waste after fly ash. It has a high impurity content and complex composition, including undecomposed phosphate rock, unwashed phosphoric acid, calcium fluoride, iron and aluminum compounds, organic matter and other impurities, resulting in low whiteness, generally light yellow, light gray or gray-black, and difficult to handle.

[0003] The storage of large amounts of phosphogypsum will not only occupy a large amount of land, but also require investment in anti-seepage treatment, otherwise it will pollute water and soil and cause serious harm to the surrounding ecological environment. Therefore, phosphogypsum needs to be comprehensively utilized. However, due to its complex composition and high impurity content, phosphogypsum can generally only be used as cement industry raw materials, chemical raw materials, soil conditioners, roadbeds or industrial fillers, etc. However, the above-mentioned utilization methods are only simple applications of phosphogypsum, and the harmful impurities in phosphogypsum are not fully removed, the resource utilization rate is low, and the added value is not high. Therefore, phosphogypsum needs to be purified and impurities removed to improve its utilization value, and through activation and modification, the application field of phosphogypsum can be expanded and the added value of phosphogypsum can be increased.

[0004] CN 110606987A discloses a pollution-free phosphogypsum filler modification method, which comprises: grinding phosphogypsum and then sieving to obtain product A; placing product A and quicklime in a stirring and heating device and stirring and mixing, adjusting the pH value of the mixture to be alkaline, specifically 8 to 12, to obtain product B; heating and stirring product B, controlling the temperature at 110 to 140°C, and heating and stirring for 35 to 70 minutes to obtain product C; sequentially adding aluminate coupling agent, calcium silicate and stearic acid to product C, continuing heating and stirring, controlling the temperature at 80 to 120°C, and heating and stirring for 35 to 55 minutes, and finally obtaining modified phosphogypsum. The modification of phosphogypsum in this method mainly involves adding alkaline substances, heating and stirring, and adding coupling agents. Under this temperature condition, the removal of bound water in the gypsum and the transformation of the crystal form are not carried out, and the impurity removal is incomplete, resulting in a limited application range of phosphogypsum, which can only be used as a filler and has limited added value.

[0005] CN 111592691A discloses a phosphogypsum-filled plastic modified particle and a preparation method thereof. The modified particle comprises phosphogypsum powder, polyolefin carrier plastic raw material, polyethylene wax, coupling agent, paraffin, antioxidant, anti-ultraviolet additive, and masterbatch. The preparation method comprises: calcining the phosphogypsum raw material at 300-600°C, cooling to room temperature, and mechanically grinding to obtain phosphogypsum powder; adding the phosphogypsum powder in a high-speed mixer, heating to 80-110°C, adding a coupling agent, and fully mixing in a high-speed mixer to perform surface activation treatment on the phosphogypsum powder; then adding other raw materials of the modified particle composition in proportion, and granulating in a granulator to obtain the phosphogypsum-filled plastic modified particle. The method involves the activation treatment of phosphogypsum and the application of preparing modified particles. The phosphogypsum raw material is not pretreated before calcination, and the presence of impurities makes it impossible to accurately control the conversion during the calcination process, and the utilization value of phosphogypsum as a filling particle is limited.

[0006] In summary, for the activation and modification of industrial by-product phosphogypsum, it is necessary to activate it based on the composition of phosphogypsum after removing impurities, so as to improve its utilization value, expand its application field, and avoid the problem of its application being restricted. Summary of the invention

[0007] In view of the problems existing in the prior art, the object of the present invention is to provide a method for activating phosphogypsum, which takes phosphogypsum as raw material, removes impurities through pretreatment and calcination, and then modifies it by grinding and adding an activator, so as to improve the activation degree of the gypsum and reduce the oil absorption value, thereby effectively improving the added value and utilization value of the phosphogypsum, helping to broaden its application field and realize the resource utilization of phosphogypsum waste.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] The present invention provides a method for activating phosphogypsum, the method comprising the following steps:

[0010] (1) mixing phosphogypsum with an inorganic acid, separating the solid and liquid after the reaction, washing, and then calcining;

[0011] (2) The phosphogypsum calcined in step (1) is cooled and then ground, and an activation modifier is added to obtain a modified gypsum product.

[0012] In the present invention, the treatment of phosphogypsum waste is mainly aimed at improving its resource utilization rate. According to the complexity of the composition of phosphogypsum, the present invention first pre-treats it with inorganic acid to remove impurities such as soluble phosphorus, fluorine and organic matter, and then calcines it to achieve full decomposition of impurities and transformation of gypsum crystal form. Finally, the calcined phosphogypsum is ground and activated, and an activator is added to modify it, so as to improve the activation degree of gypsum, reduce its oil absorption value, improve its utilization value and added value, solve the problem of its limited application in filler, and help expand the application field of phosphogypsum. The method is simple to operate, can effectively utilize the waste heat after calcination, reduce production costs, and improve competitive advantages.

[0013] The following are preferred technical solutions of the present invention, but are not intended to be limitations of the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0014] As a preferred technical solution of the present invention, the inorganic acid in step (1) includes any one of sulfuric acid, hydrochloric acid or nitric acid, or a combination of at least two of them. Typical but non-limiting examples of the combination include: a combination of sulfuric acid and hydrochloric acid, a combination of hydrochloric acid and nitric acid, a combination of sulfuric acid, hydrochloric acid and nitric acid, etc.

[0015] Preferably, the mass fraction of the inorganic acid in step (1) is 5 to 40 wt%, for example, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt% or 40 wt%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] Preferably, the solid-to-liquid ratio of the phosphogypsum to the inorganic acid in step (1) is 1g:(2-20)mL, for example 1g:2mL, 1g:4mL, 1g:6mL, 1g:8mL, 1g:10mL, 1g:12mL, 1g:15mL, 1g:18mL or 1g:20mL, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0017] As a preferred technical solution of the present invention, the reaction in step (1) is carried out under stirring conditions.

[0018] Preferably, the stirring rate is 200-800 r / min, for example 200 r / min, 300 r / min, 400 r / min, 500 r / min, 600 r / min, 700 r / min or 800 r / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] Preferably, the stirring time is 0.5 to 4 h, for example 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h or 4 h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0020] Preferably, the solid-liquid separation in step (1) comprises centrifugal separation.

[0021] Preferably, the washing in step (1) is water washing, and the pH value after washing is 4 to 6, for example 4, 4.2, 4.5, 4.8, 5, 5.2, 5.5, 5.8 or 6, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] As a preferred technical solution of the present invention, drying is performed before calcination in step (1).

[0023] Preferably, the drying temperature is 40-80°C, for example 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] Preferably, the calcination temperature in step (1) is 500-800°C, for example, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C or 800°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] Preferably, the calcination time in step (1) is 0.5 to 4 h, for example, 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h or 4 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0026] As a preferred technical solution of the present invention, the cooling in step (2) is carried out in a cooler, and cooling gas is introduced into the cooler.

[0027] Preferably, the cooling gas comprises air.

[0028] Preferably, the cooling gas flow rate in the cooler is 5% to 100% of the cooling gas flow rate at the maximum speed, for example 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] In the present invention, the heat of the calcined gypsum material is taken away by the flow of gas in the cooler to cool it down, but the temperature after cooling must meet the temperature requirement of subsequent treatment to fully utilize the waste heat of the calcined material, and the cooling gas after being heated can also be used for drying and heating of phosphogypsum before calcination to fully utilize the heat in the system; the gas flow rate of the cooler is adjusted by the speed of the cooler, and the higher the speed, the greater the gas flow rate.

[0030] Preferably, the cooling time in step (2) does not exceed 4 hours, for example 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours or 4 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] Preferably, the temperature after cooling in step (2) is 20-300°C, for example, 20°C, 50°C, 80°C, 100°C, 150°C, 200°C, 250°C or 300°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] As a preferred technical solution of the present invention, after cooling in step (2), the calcined phosphogypsum is transferred to a buffer bin until the temperature is stable, and then ground.

[0033] Preferably, the residence time of the calcined phosphogypsum in the buffer bin does not exceed 2 hours, for example 0.25 hours, 0.5 hours, 0.75 hours, 1 hour, 1.25 hours, 1.5 hours, 1.75 hours or 2 hours, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] Preferably, the temperature after temperature stabilization is 20-200°C, for example 20°C, 50°C, 80°C, 100°C, 120°C, 150°C, 180°C or 200°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] In the present invention, the buffer bin is provided to control the temperature stability of the calcined gypsum material so as to facilitate the subsequent ball milling operation.

[0036] As a preferred technical solution of the present invention, the grinding in step (2) is carried out in a grinding device, and the grinding includes ball milling.

[0037] Preferably, the frequency of the grinding in step (2) is 10 to 90 Hz, for example, 10 Hz, 20 Hz, 30 Hz, 40 Hz, 50 Hz, 60 Hz, 70 Hz, 80 Hz or 90 Hz, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0038] Preferably, the grinding time in step (2) is 10 to 300 min, for example, 10 min, 30 min, 60 min, 90 min, 120 min, 150 min, 180 min, 210 min, 240 min, 270 min or 300 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0039] Preferably, the particle size after grinding in step (2) is 200 to 2000 mesh, for example, 200 mesh, 400 mesh, 500 mesh, 750 mesh, 1000 mesh, 1200 mesh, 1500 mesh or 2000 mesh, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0040] As a preferred technical solution of the present invention, the activation modifier in step (2) includes any one of stearic acid, calcium stearate, sodium stearate, titanate or aluminate, or a combination of at least two of them. Typical but non-limiting examples of the combination include: a combination of stearic acid and calcium stearate, a combination of calcium stearate and sodium stearate, a combination of titanate and aluminate, a combination of stearic acid, calcium stearate and sodium stearate, a combination of stearic acid, titanate and aluminate, etc.

[0041] Preferably, the amount of the activation modifier added in step (2) does not exceed 10wt% of the gypsum material to be ground, for example 10wt%, 8wt%, 7wt%, 6wt%, 5wt%, 4wt%, 3wt%, 2wt% or 1wt%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0042] As a preferred technical solution of the present invention, the modified gypsum product in step (2) is used as a filling and modification raw material for polymer materials.

[0043] Preferably, the polymer material includes plastic and / or rubber.

[0044] As a preferred technical solution of the present invention, the method comprises the following steps:

[0045] (1) mixing phosphogypsum with an inorganic acid, wherein the inorganic acid comprises any one of sulfuric acid, hydrochloric acid or nitric acid or a combination of at least two thereof, wherein the mass fraction of the inorganic acid is 5 to 40 wt %, and the solid-liquid ratio of the phosphogypsum to the inorganic acid is 1 g:(2 to 20) mL, and after the reaction, solid-liquid separation and washing are performed, wherein the reaction is performed under stirring conditions, the stirring rate is 200 to 800 r / min, and the time is 0.5 to 4 h, the solid-liquid separation comprises centrifugal separation, the washing is water washing, and the pH value after washing is 4 to 6, and then drying and calcining are performed in sequence, wherein the drying temperature is 40 to 80° C., the calcining temperature is 500 to 800° C., and the calcining time is 0.5 to 4 h;

[0046] (2) cooling the phosphogypsum calcined in step (1), wherein the cooling is carried out in a cooler, wherein cooling gas air is introduced into the cooler, wherein the flow rate of the cooling gas is 5% to 100% of the flow rate of the cooling gas at the maximum speed, wherein the cooling time does not exceed 4 hours, and the temperature after the cooling is 20 to 300° C., then transferring the gypsum material to a buffer bin until the temperature is stable, wherein the residence time in the buffer bin does not exceed 2 hours, and the temperature after the temperature is stable is 20 to 200° C., then grinding is carried out, wherein the frequency of the grinding is 10 to 90 Hz, the time is 10 to 300 minutes, and the particle size after grinding is 200 to 2000 mesh, and an activation modifier is added at the same time, wherein the activation modifier comprises any one of stearic acid, calcium stearate, sodium stearate, titanate or aluminate, or a combination of at least two thereof, and the amount of the activation modifier added accounts for no more than 10 wt% of the gypsum material to be ground, thereby obtaining a modified gypsum product.

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

[0048] (1) The method of the present invention pre-treats and calcines phosphogypsum to fully remove impurities, and then modifies it by grinding and adding an activator, thereby increasing the activation degree of gypsum, reducing the oil absorption value, and improving its utilization value, thereby solving the problem of its limited application in filler applications and helping to expand the application field of phosphogypsum;

[0049] (2) The method of the present invention is easy to operate and can effectively utilize the waste heat after calcination, fully utilize the heat in the system, reduce production costs, and improve competitive advantages. DETAILED DESCRIPTION

[0050] In order to better illustrate the present invention and facilitate understanding of the technical solution of the present invention, the present invention is further described in detail below. However, the following embodiments are only simple 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.

[0051] The specific implementation of the present invention provides a method for activating phosphogypsum, which comprises the following steps:

[0052] (1) mixing phosphogypsum with an inorganic acid, separating the solid and liquid after the reaction, washing, and then calcining;

[0053] (2) The phosphogypsum calcined in step (1) is cooled and then ground, and an activation modifier is added to obtain a modified gypsum product.

[0054] The following are typical but non-limiting embodiments of the present invention:

[0055] Embodiment 1:

[0056] This embodiment provides a method for activating phosphogypsum, the method comprising the following steps:

[0057] (1) mixing phosphogypsum with hydrochloric acid, wherein the mass fraction of the hydrochloric acid is 5wt%, and the solid-liquid ratio of the phosphogypsum to the hydrochloric acid is 1g:15mL, centrifuging and washing after the reaction, wherein the reaction is carried out under stirring conditions, the stirring rate is 500r / min, and the time is 2h, the washing is water washing, and the pH value after washing is 5.6, and then drying and calcining are carried out in sequence, wherein the drying temperature is 60°C, the calcining temperature is 700°C, and the calcining time is 1.5h;

[0058] (2) cooling the phosphogypsum calcined in step (1), wherein the cooling is carried out in a cooler, cooling gas air is introduced into the cooler, the flow rate of the cooling gas is 70% of the flow rate of the cooling gas at the maximum speed, the cooling time is 1 hour, and the temperature after cooling is 180° C., then transferring the gypsum material to a buffer bin until the temperature is stable, the residence time in the buffer bin is 0.5 hour, the temperature after the temperature is stable is 150° C., then ball milling is carried out, the frequency of the ball milling is 70 Hz, the time is 90 minutes, the average particle size after ball milling is 1600 mesh, and an activation modifier is added at the same time, the activation modifier is calcium stearate, and the amount of the activation modifier added accounts for 2wt% of the gypsum material to be ball milled, to obtain a modified gypsum product.

[0059] In this embodiment, the above method is used to treat phosphogypsum, and the modified gypsum product has a high activation degree, which can reach 99.0%, and the oil absorption value can be reduced to 13. The gypsum has a high added value and is more widely used in fillers.

[0060] Embodiment 2:

[0061] This embodiment provides a method for activating phosphogypsum, the method comprising the following steps:

[0062] (1) mixing phosphogypsum with sulfuric acid, wherein the mass fraction of the sulfuric acid is 25wt%, and the solid-liquid ratio of the phosphogypsum to the sulfuric acid is 1g:5mL, centrifuging and washing after the reaction, wherein the reaction is carried out under stirring conditions, the stirring rate is 700r / min, and the time is 1h, the washing is water washing, and the pH value after washing is 4.6, and then drying and calcining are carried out in sequence, wherein the drying temperature is 80°C, the calcining temperature is 800°C, and the calcining time is 0.5h;

[0063] (2) cooling the phosphogypsum calcined in step (1), wherein the cooling is carried out in a cooler, cooling gas air is introduced into the cooler, the flow rate of the cooling gas is 85% of the flow rate of the cooling gas at the maximum speed, the cooling time is 1.5 hours, and the temperature after cooling is 150° C., then transferring the gypsum material to a buffer bin until the temperature is stable, the residence time in the buffer bin is 1 hour, the temperature after the temperature is stable is 130° C., then ball milling is carried out, the frequency of the ball milling is 50 Hz, the time is 150 minutes, the average particle size after ball milling is 1200 mesh, and an activation modifier is added at the same time, the activation modifier is sodium stearate, and the amount of the activation modifier added accounts for 4wt% of the gypsum material to be ball milled, to obtain a modified gypsum product.

[0064] In this embodiment, the above method is used to treat phosphogypsum, and the modified gypsum product has a high activation degree, which can reach 99.2%, and the oil absorption value can be reduced to 11. The gypsum has a high added value and is more widely used in fillers.

[0065] Embodiment 3:

[0066] This embodiment provides a method for activating phosphogypsum, the method comprising the following steps:

[0067] (1) mixing phosphogypsum with nitric acid, wherein the mass fraction of the nitric acid is 15wt%, and the solid-liquid ratio of the phosphogypsum to the nitric acid is 1g:10mL, centrifuging and washing after the reaction, wherein the reaction is carried out under stirring conditions, the stirring rate is 400r / min, and the time is 3h, the washing is water washing, and the pH value after washing is 5.3, and then drying and calcining are carried out in sequence, wherein the drying temperature is 50°C, the calcining temperature is 600°C, and the calcining time is 3h;

[0068] (2) cooling the phosphogypsum calcined in step (1), wherein the cooling is carried out in a cooler, wherein cooling gas air is introduced into the cooler, wherein the flow rate of the cooling gas is 60% of the flow rate of the cooling gas at the maximum speed, wherein the cooling time is 2.5 hours, and the temperature after the cooling is 100° C., then transferring the gypsum material to a buffer bin until the temperature is stable, wherein the residence time in the buffer bin is 0.75 hours, and the temperature after the temperature is stable is 75° C., then ball milling is carried out, wherein the frequency of the ball milling is 30 Hz, the time is 270 minutes, and the average particle size after the ball milling is 750 mesh, and an activation modifier is added at the same time, wherein the activation modifier is stearic acid, and the amount of the activation modifier added accounts for 6wt% of the gypsum material to be ball milled, to obtain a modified gypsum product.

[0069] In this embodiment, the above method is used to treat phosphogypsum, and the modified gypsum product has a high activation degree, which can reach 99.1%, and the oil absorption value can be reduced to 12. The gypsum has a high added value and is more widely used in fillers.

[0070] Embodiment 4:

[0071] This embodiment provides a method for activating phosphogypsum, the method comprising the following steps:

[0072] (1) mixing phosphogypsum with sulfuric acid, wherein the mass fraction of the sulfuric acid is 40wt%, and the solid-liquid ratio of the phosphogypsum to the sulfuric acid is 1g:2mL, centrifuging and washing after the reaction, wherein the reaction is carried out under stirring conditions, the stirring rate is 800r / min, and the time is 0.5h, the washing is water washing, and the pH value after washing is 4.0, and then drying and calcining are carried out in sequence, wherein the drying temperature is 70°C, the calcining temperature is 750°C, and the calcining time is 1h;

[0073] (2) cooling the phosphogypsum calcined in step (1), wherein the cooling is carried out in a cooler, wherein cooling gas air is introduced into the cooler, wherein the flow rate of the cooling gas is 100% of the flow rate of the cooling gas at the maximum speed, wherein the cooling time is 0.5 h, and the temperature after the cooling is 240° C., then transferring the gypsum material to a buffer bin until the temperature is stable, wherein the residence time in the buffer bin is 2 h, and the temperature after the temperature is stable is 180° C., then ball milling is carried out, wherein the frequency of the ball milling is 40 Hz, the time is 240 min, and the average particle size after the ball milling is 1000 mesh, and an activation modifier is added at the same time, wherein the activation modifier is aluminate, and the amount of the activation modifier added accounts for 1 wt % of the gypsum material to be ball milled, thereby obtaining a modified gypsum product.

[0074] In this embodiment, the above method is used to treat phosphogypsum, and the modified gypsum product has a high activation degree, which can reach 99.0%, and the oil absorption value can be reduced to 13. The gypsum has a high added value and is more widely used in fillers.

[0075] Embodiment 5:

[0076] This embodiment provides a method for activating phosphogypsum, the method comprising the following steps:

[0077] (1) mixing phosphogypsum with a mixed acid of hydrochloric acid and nitric acid, wherein the mass fraction of the mixed acid is 20wt%, wherein the molar ratio of hydrochloric acid to nitric acid is 1:1, and the solid-liquid ratio of the phosphogypsum to the mixed acid is 1g:8mL; centrifuging and washing after the reaction; the reaction is carried out under stirring conditions, the stirring rate is 250r / min, the time is 4h, the washing is water washing, and the pH value after washing is 6.0; then drying and calcining are carried out in sequence, the drying temperature is 40°C, the calcining temperature is 500°C, and the calcining time is 4h;

[0078] (2) cooling the phosphogypsum calcined in step (1), wherein the cooling is carried out in a cooler, wherein cooling gas air is introduced into the cooler, wherein the flow rate of the cooling gas is 50% of the flow rate of the cooling gas at the maximum speed, wherein the cooling time is 2 hours, and the temperature after the cooling is 140° C., then transferring the gypsum material to a buffer bin until the temperature is stable, wherein the residence time in the buffer bin is 1 hour, and the temperature after the temperature is stable is 100° C., then ball milling is carried out, wherein the frequency of the ball milling is 80 Hz, the time is 30 minutes, and the average particle size after the ball milling is 2000 mesh, and an activation modifier is added at the same time, wherein the activation modifier is titanate, and the amount of the activation modifier added accounts for 3wt% of the gypsum material to be ball milled, thereby obtaining a modified gypsum product.

[0079] In this embodiment, the above method is used to treat phosphogypsum, and the modified gypsum product has a high activation degree, which can reach 99.3%, and the oil absorption value can be reduced to 10. The gypsum has a high added value and is more widely used in fillers.

[0080] Comparative Example 1:

[0081] This comparative example provides a method for activating phosphogypsum, which is similar to the method in Example 1, except that no activation modifier is added in step (2).

[0082] In this comparative example, since no activation modifier was added to the gypsum material during the ball milling process, the gypsum material could not be activated. At this time, the oil absorption value of the obtained gypsum product was 50, and the modification effect was extremely poor.

[0083] Comparative Example 2:

[0084] This comparative example provides a method for activating phosphogypsum, which is similar to the method in Example 1, except that in step (1), no inorganic acid is added, but direct calcination is performed.

[0085] In this comparative example, since the phosphogypsum was not subjected to acid treatment before calcination, but only subjected to calcination to remove impurities, the impurity removal effect was limited, resulting in a poor activation degree of the subsequent gypsum material, which was between 30% and 40%.

[0086] From the above embodiments and comparative examples, it can be seen that the method of the present invention pretreats and calcines phosphogypsum to fully remove impurities, and then modifies it by grinding and adding an activator, thereby improving the activation degree of gypsum, reducing the oil absorption value, and improving its utilization value, solving the problem of its limited application in filler applications, and helping to expand the application field of phosphogypsum; the method is simple to operate, can effectively utilize the waste heat after calcination, fully utilize the heat in the system, reduce production costs, and improve competitive advantages.

[0087] The applicant declares that the present invention illustrates the detailed method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed method, that is, it does not mean that the present invention must rely on the above-mentioned detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the method of the present invention, addition of auxiliary steps, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for activating phosphogypsum, characterized in that: The method comprises the following steps: (1) mixing phosphogypsum with an inorganic acid, separating the solid and liquid after the reaction, washing, and then calcining; (2) The phosphogypsum calcined in step (1) is cooled and then ground, and an activation modifier is added to obtain a modified gypsum product.

2. The method according to claim 1, characterized in that: The inorganic acid in step (1) includes any one of sulfuric acid, hydrochloric acid or nitric acid, or a combination of at least two thereof; Preferably, the mass fraction of the inorganic acid in step (1) is 5 to 40 wt %; Preferably, the solid-to-liquid ratio of the phosphogypsum to the inorganic acid in step (1) is 1 g: (2-20) mL.

3. The method according to claim 1 or 2, characterized in that: The reaction in step (1) is carried out under stirring; Preferably, the stirring rate is 200-800 r / min; Preferably, the stirring time is 0.5 to 4 hours; Preferably, the solid-liquid separation in step (1) comprises centrifugal separation; Preferably, the washing in step (1) is water washing, and the pH value after washing is 4-6.

4. The method according to any one of claims 1 to 3, characterized in that: Step (1) drying before calcination; Preferably, the drying temperature is 40 to 80°C; Preferably, the calcination temperature in step (1) is 500-800°C; Preferably, the calcination time in step (1) is 0.5 to 4 hours.

5. The method according to any one of claims 1 to 4, characterized in that: The cooling in step (2) is carried out in a cooler, and cooling gas is introduced into the cooler; Preferably, the cooling gas comprises air; Preferably, the cooling gas flow rate in the cooler is 5% to 100% of the cooling gas flow rate at the maximum speed; Preferably, the cooling time in step (2) does not exceed 4 hours; Preferably, the temperature after cooling in step (2) is 20-300°C.

6. The method according to any one of claims 1 to 5, characterized in that: After cooling in step (2), the calcined phosphogypsum is transferred to a buffer bin until the temperature is stable, and then ground; Preferably, the residence time of the calcined phosphogypsum in the buffer bin does not exceed 2 hours; Preferably, the temperature after temperature stabilization is 20-200°C.

7. The method according to any one of claims 1 to 6, characterized in that: The grinding in step (2) is carried out in a grinding device, and the grinding includes ball milling; Preferably, the frequency of the grinding in step (2) is 10 to 90 Hz; Preferably, the grinding time in step (2) is 10 to 300 minutes; Preferably, the particle size after grinding in step (2) is 200 to 2000 mesh.

8. The method according to any one of claims 1 to 7, characterized in that: The activation modifier in step (2) includes any one of stearic acid, calcium stearate, sodium stearate, titanate or aluminate, or a combination of at least two thereof; Preferably, the amount of the activation modifier added in step (2) does not exceed 10 wt % of the gypsum material to be ground.

9. The method according to any one of claims 1 to 8, characterized in that: The modified gypsum product in step (2) is used as a filling and modification raw material for polymer materials; Preferably, the polymer material includes plastic and / or rubber.

10. The method according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: (1) mixing phosphogypsum with an inorganic acid, wherein the inorganic acid comprises any one of sulfuric acid, hydrochloric acid or nitric acid or a combination of at least two thereof, wherein the mass fraction of the inorganic acid is 5 to 40 wt %, and the solid-liquid ratio of the phosphogypsum to the inorganic acid is 1 g:(2 to 20) mL, and after the reaction, solid-liquid separation and washing are performed, wherein the reaction is performed under stirring conditions, the stirring rate is 200 to 800 r / min, and the time is 0.5 to 4 h, the solid-liquid separation comprises centrifugal separation, the washing is water washing, and the pH value after washing is 4 to 6, and then drying and calcining are performed in sequence, wherein the drying temperature is 40 to 80° C., the calcining temperature is 500 to 800° C., and the calcining time is 0.5 to 4 h; (2) cooling the phosphogypsum calcined in step (1), wherein the cooling is carried out in a cooler, wherein cooling gas air is introduced into the cooler, wherein the flow rate of the cooling gas is 5% to 100% of the flow rate of the cooling gas at the maximum speed, wherein the cooling time does not exceed 4 hours, and the temperature after the cooling is 20 to 300° C., then transferring the gypsum material to a buffer bin until the temperature is stable, wherein the residence time in the buffer bin does not exceed 2 hours, and the temperature after the temperature is stable is 20 to 200° C., then grinding is carried out, wherein the frequency of the grinding is 10 to 90 Hz, the time is 10 to 300 minutes, and the particle size after grinding is 200 to 2000 mesh, and an activation modifier is added at the same time, wherein the activation modifier comprises any one of stearic acid, calcium stearate, sodium stearate, titanate or aluminate, or a combination of at least two thereof, and the amount of the activation modifier added accounts for no more than 10 wt% of the gypsum material to be ground, thereby obtaining a modified gypsum product.