Phosphate ore calcining system and method for treating phosphate ore calcining tail gas

Abstract

The present invention provides a phosphate ore calcining system, comprising a calcining kiln and a calcining gas treatment subsystem. The calcining gas treatment subsystem includes a cyclone separator, a dust bag, a scrubbing tower, and a solid-liquid mixing tank. The cyclone separator is connected to the calcining kiln and is used to separate a first powder and a first gas-solid mixture from the calcining tail gas. The first powder is input into the solid-liquid mixing tank. The first gas-solid mixture is input into the dust bag for separation to obtain a second powder and a second gas-solid mixture. The second powder is input into the solid-liquid mixing tank. The second gas-solid mixture is input into the scrubbing tower to obtain a scrubbing liquid and a scrubbing gas. The scrubbing liquid is input into the solid-liquid mixing tank. The present invention also provides a method for treating phosphate ore calcining tail gas using the phosphate ore calcining system. The phosphate ore calcining system of the present invention improves the utilization rate of the powder in the phosphate ore calcining tail gas, thereby reducing waste emissions, saving production costs, and realizing resource utilization of materials.

Description

Technical Field

[0001] The present invention relates to the technical field of phosphate rock processing, and in particular to a phosphate rock calcining system and a method for treating phosphate rock calcining tail gas. Background Art

[0002] Phosphate rock resources are a vital national strategic resource and the material foundation of the phosphorus chemical industry. They are a key chemical mineral raw material, used to produce phosphate fertilizers and the basis for refined phosphorus chemical products such as yellow phosphorus, phosphoric acid, phosphides, and other phosphates. Phosphate rock is a non-renewable resource, and the majority of my country's phosphate rock reserves are still low- and medium-grade. This requires beneficiation to reduce the content of impurities such as carbonates and magnesium, allowing for further processing to reduce the difficulty of subsequent phosphate rock utilization. Faced with the increasing scarcity of global phosphate rock resources and the decline in rich, easily beneficiated ores, improving the utilization rate of low- and medium-grade phosphate rock has become a key development priority in my country's phosphate rock resources, crucial for the sustainable development of both the phosphorus chemical industry and agriculture.

[0003] In recent years, the production of phosphoric acid using a rotary kiln, also known as the kiln-based or blast furnace-based phosphoric acid process, has garnered widespread attention. Phosphoric acid is produced by mixing phosphate rock with other raw materials and calcining them in a rotary kiln. This process offers a high phosphorus recovery rate and significantly reduces energy consumption compared to traditional thermal phosphoric acid production processes.

[0004] Whether processing low- and medium-grade phosphate rock or producing phosphoric acid using a kiln process, phosphate rock requires calcination. This process generates a large amount of off-gas. Existing technology typically scrubs this off-gas, which contains a significant amount of carbon dioxide and can be recycled. However, the ash content of rotary kiln phosphate rock off-gas is high, typically exceeding 5%. Directly scrubbing this off-gas can clog the scrubber, resulting in insufficient ash removal and excessively high ash content in the discharged scrubber gas, impacting subsequent gas use. Furthermore, excessive ash content in the gas can waste resources. Summary of the Invention

[0005] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, in a first aspect of the present application, a phosphate ore calcining system is provided, the phosphate ore calcining system comprising a calcining kiln and a calcining gas treatment subsystem, the calcining kiln being connected to the calcining gas treatment subsystem, the calcining tail gas after the phosphate ore is calcined in the calcining kiln enters the calcining gas treatment subsystem, the calcining gas treatment subsystem comprising a cyclone separator, a dust removal bag, a washing tower and a solid-liquid mixing tank, the cyclone separator comprising a first gas-solid mixture outlet and a first powder outlet, the dust removal bag comprising a second gas-solid mixture outlet and a second powder outlet, the washing tower comprising a liquid outlet, the first powder outlet, the second powder outlet and the liquid outlet being respectively connected to the solid-liquid mixing tank, the first gas-solid mixture outlet being connected to the dust removal bag, and the second gas-solid mixture outlet being connected to the washing tower;

[0006] The cyclone separator is connected to the calcining kiln and is used to separate the calcining tail gas to obtain a first powder and a first gas-solid mixture, the first powder is input into the solid-liquid mixing tank through the first powder outlet, the first gas-solid mixture is input into the dust removal bag through the first gas-solid mixture outlet to be separated to obtain a second powder and a second gas-solid mixture, the second powder is input into the solid-liquid mixing tank through the second powder outlet, the second gas-solid mixture is input into the washing tower through the second gas-solid mixture outlet to obtain washing liquid and washing gas, and the washing liquid is input into the solid-liquid mixing tank.

[0007] In a preferred embodiment, the phosphate rock calcining system further includes a carbonization device, and the washing tower further includes a washing gas outlet, the washing gas outlet is connected to the carbonization device, and the washing gas is input into the carbonization device through the washing gas outlet.

[0008] In a preferred embodiment, the phosphate rock calcining system further includes a cooling kiln, a ball milling device and a digestion device. The phosphate rock clinker obtained by calcining the phosphate rock in the calcining kiln is input into the cooling kiln. The cooled phosphate rock clinker obtained by cooling the phosphate rock clinker in the cooling kiln is input into the ball milling device. The pulverized solid-liquid mixture obtained by ball milling the cooled phosphate rock clinker in the ball milling device is input into the digestion device.

[0009] In a preferred embodiment, the calcined phosphate rock system further includes a solvent input device, which is used to input a solvent into the solid-liquid mixing tank to form a solid-liquid mixture with the first powder, the second powder and the washing liquid in the solid-liquid mixing tank.

[0010] In a preferred embodiment, the calcined phosphate rock system further includes a central controller and a digestion device, the solid-liquid mixture in the solid-liquid mixing tank is input into the digestion device, and the central controller is used to control the second flow parameter of the solvent input device inputting the solvent according to the first flow parameter of the solid-liquid mixture entering the digestion device.

[0011] In a first aspect of the present application, a method for treating phosphate ore calcination tail gas using any one of the above phosphate ore calcination systems is provided, the method comprising the following steps:

[0012] The calcination tail gas generated by the calcination kiln is input into a cyclone separator for gas and powder separation to obtain a first powder and a first gas respectively, and the first powder is input into a solid-liquid mixing tank;

[0013] Inputting the first gas-solid mixture into a dust removal bag for dust removal to obtain a second gas-solid mixture and a second powder, and inputting the second powder into the solid-liquid mixing tank;

[0014] Passing the second gas-solid mixture into a washing tower to obtain a washing liquid and a washing gas, and inputting the washing liquid into the solid-liquid mixing tank;

[0015] A solvent is input into the solid-liquid mixing tank and mixed with the first powder, the second powder and the washing liquid to form a solid-liquid mixture, which is then input into a digestion device.

[0016] In a preferred embodiment, the mass velocity of the solvent input into the solid-liquid mixing tank is less than the mass velocity of the solid-liquid mixture output from the solid-liquid mixing tank.

[0017] In a preferred embodiment, the density of the solid-liquid mixture output from the solid-liquid mixing tank is less than 1.5 g / cubic centimeter.

[0018] In a preferred embodiment, the solid content of the solid-liquid mixture output from the solid-liquid mixing tank is less than 2.1 g / cubic centimeter.

[0019] In a preferred embodiment, the method further comprises:

[0020] The purge gas is fed into the carbonization device.

[0021] According to a third aspect of the present invention, the present invention further provides a calcium-containing compound or a magnesium-containing compound prepared by using the above-mentioned method for treating phosphate rock calcination tail gas.

[0022] According to a fourth aspect of the present invention, the present invention also provides an application of the above-mentioned method for treating phosphate rock calcination tail gas in fertilizer preparation.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention provides a phosphate rock calcining system, which transports the calcination tail gas to a calcination gas treatment subsystem, undergoes three separations through a cyclone separator, a dust removal bag, and a washing tower to obtain powder and gas. The obtained powder is transported to a solid-liquid mixing tank and fully mixed with water, and then transported to a digester for digestion treatment. This can fully utilize the powder resources in the calcination gas, effectively alleviating the above-mentioned problems. In addition, the process is simple, easy to operate, safe, reliable, efficient, low-cost, and environmentally friendly. It improves the utilization rate of powder in the phosphate rock calcination tail gas, reduces waste emissions, saves production costs, realizes resource utilization of materials, and has both economic and environmental benefits.

[0025] 2. The present invention ensures that the solid-liquid mixture can be continuously input into the digestion device by setting the parameters of feeding and discharging in the solid-liquid mixing tank. The design is reasonable, which reduces the burden of subsequent processing steps, has low cost, and stable and reliable operation.

[0026] 3. The process of the present invention is simple, easy to implement, environmentally friendly, avoids exhaust gas emissions that pollute the environment, has a high resource utilization rate, can achieve comprehensive utilization of materials, has the significant characteristics of fully utilizing resources and reducing overall costs, and has good economic, environmental and social benefits.

[0027] 4. After the solid-liquid mixture is treated by the digestion device, calcium- or magnesium-containing compounds such as calcium hydroxide or magnesium hydroxide can be obtained, which can continue to be used as industrial raw materials; or after further treatment, a solution rich in magnesium and calcium ions can be obtained, which can be applied to crops as a liquid fertilizer, or added to the production and preparation of fertilizers as a donor of magnesium and calcium elements in fertilizers. While saving the cost of fertilizer raw materials, it can be beneficial to the supplementation and absorption of crop nutrients and has good application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a structural block diagram of a phosphate rock calcining system provided in one embodiment of the present invention.

[0029] Figure 2 This is a structural schematic diagram of a calcining gas processing subsystem provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0030] The following is a preferred embodiment of the present invention. It should be noted that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

[0031] See also Figure 1 and Figure 2An embodiment of the present invention provides a phosphate rock calcining system 10, comprising a calcining kiln 100 and a calcining gas processing subsystem 200. The calcining kiln 100 is connected to the calcining gas processing subsystem 200. The calcining tail gas after the phosphate rock is calcined in the calcining kiln 100 enters the calcining gas processing subsystem 200. The calcining gas processing subsystem 200 comprises a cyclone separator 210, a dust bag 220, a washing tower 230 and a solid-liquid mixing tank 240. The cyclone separator 210 comprises a first gas-solid mixing tank. The dust removal bag 220 includes a second gas-solid mixture outlet 221 and a second powder outlet 222, and the washing tower 230 includes a liquid outlet 231. The first powder outlet 212, the second powder outlet 222 and the liquid outlet 231 are respectively connected to the solid-liquid mixing tank 240, the first gas-solid mixture outlet 211 is connected to the dust removal bag 220, and the second gas-solid mixture outlet 221 is connected to the washing tower 230.

[0032] The cyclone separator 210 is connected to the calcining kiln 100 and is used to separate the calcining tail gas to obtain a first powder and a first gas-solid mixture. The first powder is input into the solid-liquid mixing tank 240 through the first powder outlet 212, and the first gas-solid mixture is input into the dust removal bag 220 through the first gas-solid mixture outlet 211 to be separated to obtain a second powder and a second gas-solid mixture. The second powder is input into the solid-liquid mixing tank 240 through the second powder outlet 222, and the second gas-solid mixture is input into the washing tower 230 through the second gas-solid mixture outlet 221 to obtain washing liquid and washing gas, and the washing liquid is input into the solid-liquid mixing tank 240.

[0033] In order to alleviate the problems of calcining tail gas generated by calcining phosphate ore directly being sent to a water washing tower for water washing, which easily leads to blockage, insufficient washing, and affects the reuse of powder resources in the calcining tail gas, the present invention provides a phosphate ore calcining system 10. The system transports the calcining tail gas to a calcining gas treatment subsystem, and separates it three times through a cyclone separator 210, a dust removal bag 220, and a washing tower 230 to obtain powder and gas. The obtained powder is transported to a solid-liquid mixing tank 240 and fully mixed with water, and then transported to a digester for digestion treatment. The powder resources in the calcining gas can be fully utilized, effectively alleviating the above-mentioned problems. In addition, the process is simple, easy to operate, safe, reliable, efficient, low-cost, and environmentally friendly, thereby improving the utilization rate of powder in the phosphate ore calcining tail gas, reducing waste emissions, saving production costs, and realizing resource utilization of materials, with dual economic and environmental benefits.

[0034] It should be noted that the "powder" in the above-mentioned first powder and second powder can also be called "ash" or "dust", which is the solid residue after the calcination of phosphate rock.

[0035] It is understandable that the solid residual powder in the tail gas after calcining phosphate rock is a mixture mainly containing calcium oxide (CaO) and magnesium oxide (MgO), and the gas in the tail gas after calcining phosphate rock is a gas mainly containing carbon dioxide.

[0036] In a further embodiment, the phosphate rock calcining system 10 further includes a carbonization device 300, and the scrubbing tower 230 further includes a scrubbing gas outlet 232. The scrubbing gas outlet 232 is connected to the carbonization device 300, and the scrubbing gas is input into the carbonization device 300 through the scrubbing gas outlet 232. The scrubbing gas is mainly carbon dioxide.

[0037] In a further embodiment, the phosphate rock calcining system 10 further includes a cooling kiln 400, a ball milling device 500 and a digestion device 600. The phosphate rock clinker obtained after calcining the phosphate rock in the calcining kiln 100 is input into the cooling kiln 400. The cooled phosphate rock clinker obtained by cooling the phosphate rock clinker in the cooling kiln 400 is input into the ball milling device 500. The crushed solid-liquid mixture obtained by ball milling the cooled phosphate rock clinker in the ball milling device 500 is input into the digestion device 600. The solid-liquid mixture in the solid-liquid mixing tank 240 is input into the digestion device 600.

[0038] In a further embodiment, the solid-liquid mixing tank 240 is provided with a stirring device. According to the present invention, the stirring device provided in the solid-liquid mixing tank 240 can achieve a more uniform mixing of the powder and the solvent in the solid-liquid mixing tank 240 through stirring, thereby better dispersing the powder in the solvent and achieving excellent mixing of the materials. Preferably, the stirring device includes a stirring shaft, stirring blades disposed on the stirring shaft, and a motor for driving the stirring shaft.

[0039] In a further embodiment, the digestion device 600 is provided with a stirring device.

[0040] According to the present invention, in the calcination gas processing subsystem 200, the calcination tail gas is fully separated into gas and solids to obtain a gas mainly containing carbon dioxide and a solid residue of the calcined phosphate rock. In the solid-liquid mixing tank 240, the solvent and the powder (i.e., the first powder, the second powder, and the washing liquid) are fully mixed to obtain a solid-liquid mixture that can be continuously added to the digester. That is, the setting of the solid-liquid mixing tank 240 in the method ensures that the solid-liquid mixture can be continuously input into the digestion device 600. In the digestion device 600, the calcium oxide in the solid residue of the calcined phosphate rock can be subjected to a digestion reaction to obtain calcium hydroxide, and the magnesium oxide can be subjected to a digestion reaction to obtain magnesium hydroxide, thereby realizing resource utilization of the materials and having better application value. The obtained carbon dioxide gas can be used to be input into a carbonization device to prepare ammonium nitrate calcium magnesium liquid, or carbonized to prepare calcium magnesium carbonate, which is applied to the production and preparation of fertilizers. Therefore, the system provided by the present invention is not only environmentally friendly, but also saves raw material costs, improves resource utilization, and can achieve comprehensive and integrated utilization of materials, with the significant characteristics of fully utilizing resources and reducing overall costs.

[0041] It should be noted that the present invention has no particular limitation on the type and source of phosphate rock and solvent, and those commonly used in the art may be used as long as they do not limit the purpose of the present invention.

[0042] In a preferred embodiment, the phosphate rock comprises at least one of low-grade phosphate rock, medium-grade phosphate rock or phosphate concentrate;

[0043] It should be understood that the grade of phosphate rock primarily refers to the P2O5 content within the phosphate rock. Based on the P2O5 content within the phosphate rock, phosphate rock can be classified as high-grade, medium-grade, and low-grade. The aforementioned low-grade and medium-grade phosphate rocks may also be referred to as medium-low-grade phosphate rock, and the aforementioned phosphate concentrate may also be referred to as high-grade phosphate rock. The specific meanings of the terms "low-grade phosphate rock," "medium-grade phosphate rock," "medium-low-grade phosphate rock," "high-grade phosphate rock," and "phosphate concentrate" are well-known to those skilled in the art and are not specifically limited in the present invention and will not be described in detail. These terms are generally understood in the art.

[0044] The main purpose of the present invention is to treat the calcination tail gas generated by calcination. There is no special limitation on the specific process of calcining the phosphate ore. For example, the calcination tail gas can be generated by calcining the phosphate ore in a rotary kiln. The specific operating conditions of the rotary kiln are also known to those skilled in the art and will not be described in detail here.

[0045] According to the present invention, the phosphate rock can be one or more of low-grade phosphate rock, medium-grade phosphate rock, or phosphate concentrate; and the solvent can be water or other commonly used solvents in the art, such as acids, bases, and alcohols. Preferably, water is used as the solvent to facilitate subsequent digestion treatment, while also being cost-effective, easy to operate, and easy to mix.

[0046] In a further embodiment, the calcined phosphate rock system 10 further includes a solvent input device 700, which is used to input a solvent into the solid-liquid mixing tank 240. The solvent, the first powder, the second powder, and the washing liquid form a solid-liquid mixture in the solid-liquid mixing tank 240.

[0047] In a further embodiment, the calcined phosphate rock system 10 further includes a central controller (not shown) and a digestion unit 600. The solid-liquid mixture from the solid-liquid mixing tank 240 is input into the digestion unit 600. The central controller is configured to control a second flow rate parameter of the solvent inputted by the solvent input device based on a first flow rate parameter of the solid-liquid mixture entering the digestion unit 600. The first flow rate parameter is the mass velocity of the solvent, and the second flow rate parameter is the mass velocity of the solid-liquid mixture outputted from the solid-liquid mixing tank 240. By controlling the mass velocity of the solvent entering the digestion unit 600 and the mass velocity of the solid-liquid mixture flowing out of the digestion unit 600 by the central controller, the density or solid content of the solid-liquid mixture in the solid-liquid mixing tank 240 can be ensured to be within a preset value, or in other words, the solid-liquid mixture can be ensured to have an optimal density for reaction in the digestion unit 600.

[0048] In a further embodiment, a first detection device (not shown) is provided at the first gas-solid mixture outlet 211 of the cyclone separator 210. The first detection device is used to detect the solid content of the first gas-solid mixture in the first gas-solid mixture outlet 211. When the first detection device detects that the solid content of the first gas-solid mixture is less than a preset value, the separation speed of the cyclone separator 210 needs to be adjusted to accelerate the gas-solid separation of the calcination tail gas.

[0049] In a further embodiment, the calcined phosphate rock system 10 further includes a central controller connected to the cyclone separator 210 and the first detection device, configured to receive first detection information from the first detection device and control the separation speed of the cyclone separator 210 based on the first detection information. The first detection information is the solid content in the first gas-solid mixture.

[0050] In a further embodiment, a second detection device (not shown) is provided in the solid-liquid mixing tank 240. The second detection device is used to detect the density or solid content of the solid-liquid mixture in the solid-liquid mixing tank 240. The central controller is also connected to the second detection device and is used to receive second detection information from the second detection device. When the second detection information exceeds a preset value, the central controller controls the solvent input device to input a second flow parameter of the solvent to ensure that the density or solid content of the solid-liquid mixture in the solid-liquid mixing tank 240 is within the preset value. The second detection information is the density or solid content of the solid-liquid mixture in the solid-liquid mixing tank.

[0051] In a further embodiment, the digestion device 600 includes a digester, a digester, and a grinding device;

[0052] Preferably, the grinding device is a ball mill, and the ball mill is preferably a wet ball mill.

[0053] According to the present invention, the digestion device 600 is mainly used to perform digestion reaction on the solid-liquid mixture. There is no special restriction on the specific structure and type of the digestion device 600. As long as the digestion reaction can be effectively carried out, it will not limit the purpose of the present invention.

[0054] The digestion device 600 can be used to generate calcium hydroxide after calcium oxide is digested with water, or to generate magnesium hydroxide after magnesium oxide is digested with water. The operation is simple, resource utilization is high, and the application value of the product is improved.

[0055] See also Figure 1 and Figure 2 In one embodiment of the present invention, a method for treating phosphate ore calcination tail gas using any of the above-described phosphate ore calcination systems 10 is provided. The method comprises the following steps S100, S200, S300, and S400. The detailed steps are as follows.

[0056] Step S100: The calcination tail gas generated by the calcination kiln 100 is input into the cyclone separator 210 for gas and powder separation to obtain a first powder and a first gas-solid mixture, respectively. The first powder is input into the solid-liquid mixing tank 240;

[0057] Step S200: inputting the first gas-solid mixture into the dust removal bag 220 for dust removal to obtain a second gas-solid mixture and a second powder, and inputting the second powder into the solid-liquid mixing tank 240;

[0058] Step S300, introducing the second gas-solid mixture into the scrubbing tower 230 to obtain scrubbing liquid and scrubbing gas, and the scrubbing liquid is input into the solid-liquid mixing tank 240;

[0059] In step S400 , a solvent is input into the solid-liquid mixing tank 240 , mixed with the first powder, the second powder and the washing liquid to form a solid-liquid mixture, and the solid-liquid mixture is input into the digestion device 600 .

[0060] In a further embodiment, the method further includes: adjusting the mass rate of the solvent input to the solid-liquid mixing tank 240 according to the mass rate of the powder input to the output of the solid-liquid mixing tank.

[0061] In a further embodiment, the method further includes: detecting the solid content in the first gas-solid mixture, and adjusting the separation speed of the cyclone separator 210 according to the solid content in the first gas-solid mixture.

[0062] In a further embodiment, the mass velocity of the solvent input into the solid-liquid mixing tank 240 is less than the mass velocity of the solid-liquid mixture output from the solid-liquid mixing tank 240. The solvent is preferably water.

[0063] Preferably, the mass velocity of the solvent input to the solid-liquid mixing tank 240 is 0.0001-0.01 times, preferably 0.0008-0.002 times, the mass velocity of the powder output from the solid-liquid mixing tank 240. The powder includes the first powder, the second powder and the washing liquid.

[0064] Preferably, the volume velocity of the solvent input into the solid-liquid mixing tank 240 is 0.01 to 0.9 times, preferably 0.1 to 0.5 times, the mass velocity of the solid-liquid mixture output from the solid-liquid mixing tank 240 .

[0065] In a further embodiment, the density of the solid-liquid mixture output from the solid-liquid mixing tank 240 is less than 1.5 g / cubic centimeter.

[0066] In a further embodiment, the solid content of the solid-liquid mixture output from the solid-liquid mixing tank 240 is less than 2.1 g / cubic centimeter.

[0067] In a further embodiment, the method further comprises inputting the purge gas into the carbonization device 300. The purge gas is carbon dioxide.

[0068] In a preferred embodiment, the feed flow rate of the calcined tail gas is 500 to 50000 m 3 / h, preferably 10000~15000m 3 The feed flow rate of the calcined tail gas is the speed at which it enters the cyclone separator.

[0069] Preferably, in the solid-liquid mixing tank, the feed flow rate of the powder is 100 to 1000 kg / h, preferably 400 to 600 kg / h;

[0070] Preferably, in the solid-liquid mixing tank, the solvent feed flow rate is 0.1 to 10 m 3 / h, preferably 0.4 to 0.6 m 3 / h;

[0071] Preferably, in the solid-liquid mixing tank, the discharge flow rate of the solid-liquid mixture is 1 to 100 m 3 / h, preferably 4 to 6m 3 / h.

[0072] According to the present invention, the calcined tail gas passes through cyclone separator 210 to separate powder and gas. The first gas-solid mixture, after separation of the first powder, enters dust bag 220 for further separation of powder and gas. The second gas-solid mixture, after separation of the second powder, enters scrubbing tower 230 to separate the scrubbing gas and scrubbing liquid. The solid-liquid mixing tank 240 is equipped with corresponding powder inlet, solvent inlet, and solid-liquid mixture outlet. Water is continuously replenished through the solvent inlet, separated powder is continuously replenished through the powder inlet, and the solid-liquid mixture outlet continuously discharges the solid-liquid mixture into the digestion unit 600.

[0073] The solvent feed rate at the solvent inlet is lower than the solid-liquid mixture discharge rate at the solid-liquid mixture outlet; the solvent feed rate is lower than the powder feed rate at the powder inlet. Setting appropriate feed and discharge rates helps enhance the mixing effect of the powder and water, achieving better mixing and facilitating subsequent digestion reactions.

[0074] It is understandable that the amount of water delivered should not be too much or too fast, because this will not only fail to provide a good buffering effect and cause waste, but will also increase the burden on subsequent digestion reactions.

[0075] It is understandable that the feed rate of the above-mentioned powder, the feed rate of the solvent, and the discharge rate of the solid-liquid mixture are related to the volume of the solid-liquid mixing tank 240, and the feed and discharge rates of the materials need to be adjusted accordingly according to the volume of the solid-liquid mixing tank 240. If the volume of the solid-liquid mixing tank 240 is small, and the feed and discharge rates are large, this may result in the powder and water being discharged directly before they are evenly mixed, which not only fails to have a buffering effect, but also easily leads to blockage of the pipeline. On the contrary, if the volume of the solid-liquid mixing tank 240 is too large, the buffering effect may be enhanced, but it will also lead to excessively high costs, excessive space occupation, and waste. Therefore, in actual production, it is necessary to appropriately adjust the feed rate of the powder, the feed rate of the solvent, and the discharge rate of the solid-liquid mixture according to the volume of the solid-liquid mixing tank 240.

[0076] According to the present invention, the specifications or separation speed of the cyclone separator 210 can be set according to the ash content in the gas. For example, the specifications and speed of the cyclone separator 210 can be set so that the ash content in the gas after ash separation is less than 2%.

[0077] It should be understood that the contents not described in detail in the description of the above treatment method are all common parameters that can be easily thought of by those skilled in the art and can be adjusted by those skilled in the art according to actual conditions, such as the speed of rotation and stirring, etc., so detailed description thereof can be omitted.

[0078] In at least one embodiment, the present invention provides a calcium-containing compound or a magnesium-containing compound prepared by using the above-mentioned method for treating phosphate rock calcination tail gas.

[0079] The present invention provides, in at least one embodiment, an application of the method for treating phosphate rock calcination tail gas in fertilizer preparation.

[0080] It is understandable that the preparation of the calcium-containing compound or magnesium-containing compound and the application thereof in the above-mentioned embodiments of the present invention are based on the same inventive concept as the aforementioned method for treating phosphate ore calcination tail gas, and therefore have at least the same advantages as the aforementioned method for treating phosphate ore calcination tail gas, which will not be described in detail here.

[0081] It should be noted that the above-mentioned calcium-containing compound or magnesium-containing compound is mainly obtained by subsequent treatment of a solid-liquid mixture, and can be calcium hydroxide and magnesium hydroxide, or other products containing calcium and magnesium elements, such as calcium nitrate, calcium carbonate, magnesium nitrate, magnesium carbonate, etc. In addition, the above-mentioned calcium-containing compound and magnesium-containing compound can be used in the production and preparation of fertilizers. In addition, the gas after treatment in the water scrubber can also be used in the production and preparation of fertilizers.

[0082] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A phosphate rock calcining system, characterized in that: The phosphate rock calcining system includes a calcining kiln and a calcining gas processing subsystem, the calcining kiln is connected to the calcining gas processing subsystem, and the calcining tail gas after the phosphate rock is calcined in the calcining kiln enters the calcining gas processing subsystem, the calcining gas processing subsystem includes a cyclone separator, a dust removal bag, a washing tower and a solid-liquid mixing tank, the cyclone separator includes a first gas-solid mixture outlet and a first powder outlet, the dust removal bag includes a second gas-solid mixture outlet and a second powder outlet, the washing tower includes a liquid outlet, the first powder outlet, the second powder outlet and the liquid outlet are respectively connected to the solid-liquid mixing tank, the first gas-solid mixture outlet is connected to the dust removal bag, and the second gas-solid mixture outlet is connected to the washing tower; The cyclone separator is connected to the calcining kiln and is used to separate the calcining tail gas into a first powder and a first gas-solid mixture, the first powder is input into the solid-liquid mixing tank through the first powder outlet, the first gas-solid mixture is input into the dust removal bag through the first gas-solid mixture outlet for separation to obtain a second powder and a second gas-solid mixture, the second powder is input into the solid-liquid mixing tank through the second powder outlet, the second gas-solid mixture is input into the washing tower through the second gas-solid mixture outlet to obtain a washing liquid and a washing gas, and the washing liquid is input into the solid-liquid mixing tank; The phosphate rock calcining system further includes a solvent input device, which is used to input a solvent into the solid-liquid mixing tank to form a solid-liquid mixture with the first powder, the second powder and the washing liquid in the solid-liquid mixing tank; The phosphate rock calcining system further includes a central controller and a digestion device, wherein the solid-liquid mixture in the solid-liquid mixing tank is input into the digestion device, and the central controller is used to control a second flow rate parameter of the solvent input by the solvent input device according to a first flow rate parameter of the solid-liquid mixture entering the digestion device, so that the mass velocity of the solvent input by the solvent input device into the solid-liquid mixing tank is less than the mass velocity of the solid-liquid mixture output from the solid-liquid mixing tank; A first detection device is provided at the outlet of the first gas-solid mixture of the cyclone separator. The central controller is connected to the cyclone separator and the first detection device, and is used to receive first detection information from the first detection device. The first detection information is the solid content in the first gas-solid mixture. The central controller is also used to control the separation speed of the cyclone separator according to the first detection information, thereby indirectly controlling the solid content of the first powder output from the first powder outlet of the cyclone separator, so that the feed rate of the solvent in the solid-liquid mixing tank is less than the feed rate of the powder at the powder inlet of the solid-liquid mixing tank.

2. The phosphate rock calcining system according to claim 1, characterized in that: The phosphate rock calcining system further includes a carbonization device, and the washing tower further includes a washing gas outlet, which is connected to the carbonization device, and the washing gas is input into the carbonization device through the washing gas outlet.

3. The phosphate rock calcining system according to claim 1, characterized in that: The phosphate rock calcining system also includes a cooling kiln, a ball milling device and a digestion device. The phosphate rock clinker obtained by calcining the phosphate rock in the calcining kiln is input into the cooling kiln. The cooled phosphate rock clinker obtained by cooling the phosphate rock clinker in the cooling kiln is input into the ball milling device. The pulverized solid-liquid mixture obtained by ball milling the cooled phosphate rock clinker in the ball milling device is input into the digestion device.

4. A method for treating phosphate ore calcining tail gas using the phosphate ore calcining system according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: The calcination tail gas generated by the calcination kiln is input into a cyclone separator for gas and powder separation to obtain a first powder and a first gas-solid mixture respectively, and the first powder is input into a solid-liquid mixing tank; Inputting the first gas-solid mixture into a dust removal bag for dust removal to obtain a second gas-solid mixture and a second powder, and inputting the second powder into the solid-liquid mixing tank; Passing the second gas-solid mixture into a washing tower to obtain a washing liquid and a washing gas, and inputting the washing liquid into the solid-liquid mixing tank; A solvent is input into the solid-liquid mixing tank and mixed with the first powder, the second powder and the washing liquid to form a solid-liquid mixture, which is then input into a digestion device.

5. The method according to claim 4, characterized in that The density of the solid-liquid mixture output from the solid-liquid mixing tank is less than 1.5 g / cubic centimeter.

6. The method according to claim 4, characterized in that The solid content of the solid-liquid mixture output from the solid-liquid mixing tank is less than 2.1 g / cubic centimeter.

7. The method according to claim 4, characterized in that The method further comprises: The purge gas is fed into the carbonization device.

Images