CN114772559A - Separation type dual system and production method for preparing sulfuric acid co-production cement with phosphogypsum - Google Patents

Abstract

The invention discloses a separate dual system and a production method for preparing sulfuric acid co-production cement from phosphogypsum. The separate dual system includes a phosphogypsum pyrolysis acid-making system and a cement clinker calcining system. The invention adopts a separate phosphogypsum pyrolysis device, and separates the phosphogypsum pyrolysis sulfuric acid system and the cement clinker calcining system, so that the operator can at any time according to the different pyrolysis environments required by the phosphogypsum and other cement raw materials. Adjusting the working conditions avoids the risk of crusting and clogging of the decomposition furnace due to the excessively high pyrolysis temperature required for phosphogypsum and the production of a large amount of liquid phase. While the decomposition rate of phosphogypsum is improved, the quality of cement clinker is ensured; at the same time, it improves the The universality of phosphogypsum, and the SO ₂ concentration in the obtained acid-making flue gas is not less than 8%.

Description

Separation dual system and production method for preparing sulfuric acid co-production cement with phosphogypsum

technical field

The invention relates to the technical field of preparing sulfuric acid co-production cement from phosphogypsum, in particular to a separate dual system and production method for preparing sulfuric acid co-production cement from phosphogypsum.

Background technique

Phosphogypsum is an industrial waste residue produced in the process of preparing phosphoric acid from sulfuric acid. With the development of my country's economy, the increase in demand for phosphate fertilizers has led to a rapid increase in the total amount of phosphogypsum stockpiles in recent years. Due to the complex impurities contained in phosphogypsum, there are serious restrictions on its resource utilization, and a large number of storage not only occupy land resources, but also contain water-soluble phosphorus pentoxide and water-soluble fluorine directly threatening the environmental safety of surrounding waters. The large-scale development and utilization of gypsum cannot be delayed.

Because phosphogypsum is rich in calcium and sulfur resources, the technology of decomposing phosphogypsum to produce sulfuric acid and co-producing cement can not only make full use of the calcium and sulfur resources in it, but also do not discharge solid waste during the production process, and also provide sulfuric acid for phosphate fertilizer enterprises. The production of raw materials has good economic and environmental benefits. However, the decomposition characteristics of phosphogypsum and limestone are quite different. The decomposition temperature of phosphogypsum is high, and the control of the decomposition atmosphere is difficult. From the perspective of energy saving and emission reduction, the application of fluidized decomposition technology to the pyrolysis of phosphogypsum to produce sulfuric acid co-produced cement is the development direction of this process.

As early as 1997, Lubei Group adopted this technology with the goal of 10-fold enlargement of the "3, 4, 6" PSC projects, to achieve an annual production capacity of 300,000 tons of ammonium phosphate and 400,000 tons of sulfuric acid to jointly produce 600,000 tons of cement. . However, during the operation of the system, the decomposition furnace at the end of the kiln is prone to crusting and blockage, and the decomposition process outside the kiln eventually failed to achieve the original design capacity. At present, the problems existing in the process of decomposing acid and co-producing cement outside the kiln are: 1) Most of the phosphate rock in my country is of medium and low grade, and correspondingly, the impurity content of phosphogypsum is relatively high. According to incomplete statistics, the average content of phosphogypsum SiO ₂ in China is about 10%, the average content of P ₂ O ₅ is about 1.15%, and the average content of F is about 0.40%. Therefore, most of the phosphogypsum in my country cannot be directly used for acid production and cement production. 2) The full combustion of coal and the formation of high-quality clinker both require an oxidizing atmosphere, while the decomposition of phosphogypsum requires a reducing atmosphere. This is a pair of contradictions that are difficult to reconcile, and the production control is difficult, resulting in large fluctuations in the quality of cement clinker. 3) Since the decomposition temperature of gypsum (pure CaSO ₄ ), the main component of phosphogypsum, is higher than the lowest eutectic point of phosphogypsum raw meal (in addition to CaSO ₄ , it also contains SiO ₂ , Fe ₂ O ₃ and other mixtures), it is in a stacked state. The inner part of the phosphogypsum, which has not been completely decomposed, stops decomposing because it is wrapped by the liquid phase that appears prematurely in the raw meal, which reduces the quality of the cement. ₄ ) The SO2 gas concentration in the flue gas for acid production is generally required to be more than 8%, and because the decomposition of phosphogypsum and the calcination of cement clinker are all carried out in one device, the calcination temperature of cement clinker is as high as 1300-1450 ° C, and the system gas demand Therefore, under normal conditions, the SO ₂ concentration of the kiln tail gas is generally only about 6%, which brings difficulties to acid production.

SUMMARY OF THE INVENTION

The object of the present invention is to overcome the above-mentioned technical deficiencies, propose a separate dual system and production method for preparing sulfuric acid co-production cement with phosphogypsum, and solve the problem that the phosphogypsum has poor universality and production in the prior art. The technical problems of difficult control and low SO ₂ content in acid-making flue gas.

The first aspect of the present invention provides a separate dual system for preparing sulfuric acid co-production cement from phosphogypsum, including: a phosphogypsum pyrolysis acid-making system and a cement clinker calcining system; wherein,

The phosphogypsum pyrolysis acid production system includes: phosphogypsum preheating device, phosphogypsum pyrolysis device, high temperature gas-solid separator and acid production device; the solid phase outlet of the phosphogypsum preheating device and the solid phase inlet of the phosphogypsum pyrolysis device Connection, the material outlet of the phosphogypsum pyrolysis device is connected with the material inlet of the high-temperature gas-solid separator, the gas-phase outlet of the high-temperature gas-solid separator is connected with the gas-phase inlet of the phosphogypsum preheating device, and the gas-phase outlet of the phosphogypsum preheating device is connected with the gas-phase inlet of the phosphogypsum preheating device. Gas phase inlet connection of acid plant;

The cement clinker calcining system includes raw meal preheating device, enlarged gas-solid separator, mixing device and rotary kiln; The phase outlet is connected, the material outlet of the mixing device is connected with the material inlet of the enlarged gas-solid separator, and the solid phase outlet of the enlarged gas-solid separator is connected with the material inlet of the rotary kiln.

A second aspect of the present invention provides a process for preparing sulfuric acid co-production cement from phosphogypsum, comprising the following steps:

Phosphogypsum pyrolysis for acid production: phosphogypsum conducts gas-solid two-phase heat exchange in the phosphogypsum preheating device, and then enters the phosphogypsum pyrolysis device for pyrolysis reaction after preheating to above 800 °C, and enters the high-temperature gas-solid separator after the reaction is complete. Gas-solid separation is carried out in the process, and the generated hot new calcium enters the mixing device. The waste gas containing high concentration SO ₂ is collected by the phosphogypsum preheating device, and sulfuric acid is obtained in the acid making device; the internal temperature of the phosphogypsum pyrolysis device is 1000 ℃ -1250℃; in the process of phosphogypsum pyrolysis for acid production, the pulverized coal used is at least one of bituminous coal, anthracite and lignite, and the calorific value is in the range of 4000-8000kcal/kg; the input amount of pulverized coal is calculated according to the carbon-sulfur ratio of 1.1-2.0 coal input;

Cement clinker calcination: The raw meal passes through the raw meal preheating device for heat exchange, and then is mixed with the hot new calcium obtained by the pyrolysis of phosphogypsum in the mixing device. The solid phase material enters the rotary kiln for calcination to obtain cement clinker;

Compared with the prior art, the beneficial effects of the present invention include:

(1) A separate phosphogypsum pyrolysis device is used, and the phosphogypsum pyrolysis sulfuric acid system and the cement clinker calcining system are separated, so that operators can make different pyrolysis environments according to the needs of phosphogypsum and other cement raw materials. Adjust the working conditions at any time to avoid the risk of crusting and clogging of the decomposition furnace due to the excessively high pyrolysis temperature required for phosphogypsum, and to ensure the quality of cement clinker while increasing the decomposition rate of phosphogypsum;

(2) Compared with the traditional phosphogypsum decomposition technology outside the kiln, after the pyrolysis of phosphogypsum is completed, the waste gas containing high concentration SO ₂ is discharged and collected with the phosphogypsum preheating device of the phosphogypsum pyrolysis system for sulfuric acid production. Compared with the collection of SO ₂ at the exhaust gas outlet, it is undoubtedly more advantageous. The test shows that the SO ₂ concentration in the flue gas is not less than 8%;

(3) The universality of phosphogypsum is improved. According to the difference in the impurity content of phosphogypsum, it can be solved by adjusting the raw meal formula and parameters such as the carbon-sulfur ratio of the phosphogypsum pyrolysis device, and finally the clinker that meets the quality requirements can be obtained. .

Description of drawings

1 is a schematic structural diagram of an embodiment of a separate dual system for preparing sulfuric acid co-production cement from phosphogypsum of the present invention;

Fig. 2 is the structural representation of the original 2500t/d new dry process cement clinker production line; wherein, the precalciner is a precalciner with a precombustion furnace;

Fig. 3 is the structural representation of the original 2000t/d new dry process cement clinker production line; wherein, the decomposition furnace is a spouting type decomposition furnace;

Figure 4 is a schematic structural diagram of the original 5000t/d new dry process cement clinker production line; wherein, the calciner is a spray-rotation combined calciner.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

In the description of the present invention, it should be noted that, unless otherwise expressly specified and limited, the terms "connected" and "connected" should be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be a direct connection, or an indirect connection through an intermediate medium, or an internal connection between two components. Connected. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

Referring to FIG. 1 , a first aspect of the present invention provides a separate dual system for preparing sulfuric acid co-production cement from phosphogypsum, including: a system 1 for producing acid by pyrolysis of phosphogypsum and a system 2 for calcining cement clinker. Among them, the phosphogypsum pyrolysis acid production system 1 includes: a phosphogypsum preheating device 11, a phosphogypsum pyrolysis device 12, a high temperature gas-solid separator 13 and an acid production device 14, the solid phase outlet of the phosphogypsum preheating device 11 is connected to the phosphorus The solid phase inlet of the gypsum pyrolysis device 12 is connected, the material outlet of the phosphogypsum pyrolysis device 12 is connected to the material inlet of the high-temperature gas-solid separator 13, and the gas-phase outlet of the high-temperature gas-solid separator 13 is connected to the gas phase of the phosphogypsum preheating device 11. The inlet is connected, and the gas phase outlet of the phosphogypsum preheating device 11 is connected to the gas phase inlet of the acid making device 14; the cement clinker calcining system 2 includes a raw meal preheating device 21, an enlarged gas-solid separator 22, a mixing device 23 and a rotary kiln 24. The solid phase inlet of the mixing device 23 is respectively connected with the solid phase outlet of the raw meal preheating device 21 and the solid phase outlet of the high temperature gas-solid separator 13, and the material outlet of the mixing device 23 is connected with the material of the enlarged gas-solid separator 22. The inlet is connected, and the solid phase outlet of the enlarged gas-solid separator 22 is connected with the material inlet of the rotary kiln 24 .

The main work flow of the system of the present invention includes: since phosphogypsum easily reacts with carbon to generate CaS at 500°C _- 800°C, and CaS is difficult to pyrolyze and desulfurize compared with CaSO4, so in order to reduce heat consumption and improve the desulfurization rate of phosphogypsum, The phosphogypsum undergoes gas-solid two-phase heat exchange in the phosphogypsum preheating device 11, and then enters the phosphogypsum pyrolysis device 12 for pyrolysis reaction after preheating to above 800 °C. The temperature of the phosphogypsum pyrolysis device 12 is controlled at 1000 °C-1250 ℃, after the reaction is complete, it enters the high-temperature gas-solid separator 13 with the hot air flow for gas-solid separation, and the solid-phase product after the pyrolysis of phosphogypsum (hereinafter referred to as hot-state fresh calcium) enters the mixing device 23, and contains high-concentration SO ₂ . The waste gas enters the phosphogypsum preheating device 11, and after heat exchange, the waste gas with high concentration SO ₂ (temperature at 300-400 ° C) enters the acid making device 14 to obtain sulfuric acid; The hot new calcium powder obtained by pyrolysis of gypsum is mixed uniformly in the mixing device 23 . The mixed material is gas-solid separated in the enlarged gas-solid separator 22, and the solid-phase material enters the rotary kiln 24 for calcination to obtain cement clinker. Due to the use of the phosphogypsum pyrolysis device 12, the phosphogypsum is changed from the traditional accumulation state decomposition to the fluidized state decomposition, thereby greatly improving the decomposition efficiency, and finally achieving the purpose of reducing the heat consumption of the entire firing system. The invention breaks through the technical bottleneck brought by using fluidized pyrolysis technology to realize the preparation of phosphogypsum to co-produce cement clinker with sulfuric acid, provides technical support for large-scale resource utilization of phosphogypsum, realizes large consumption of phosphogypsum, and uses The purpose of reducing carbon and increasing efficiency of cement.

Preferably, the gas-phase outlet of the enlarged gas-solid separator 22 is connected to the gas-phase inlet of the raw meal preheating device 21 .

Preferably, the flue gas outlet of the rotary kiln 24 is connected to the gas phase inlet of the mixing device 23, so that the flue gas generated by the rotary kiln 24 directly enters the mixing device 23 and is discharged from the raw meal preheating device 21, and the flue gas is strictly prohibited from entering the acid production. system.

Preferably, the tertiary air outlet of the kiln head cover of the rotary kiln 24 is connected with the hot air inlet of the phosphogypsum pyrolysis device 12, so that the air required for the phosphogypsum pyrolysis reaction is provided by the kiln head tertiary air.

Further, the hot air inlet of the phosphogypsum pyrolysis device 12 is arranged at the bottom and the side cone portion of the phosphogypsum pyrolysis device 12, so that the tertiary air introduced by the kiln head cover can pass through the bottom and side cone portions of the phosphogypsum pyrolysis device 12 respectively. Entering the phosphogypsum pyrolysis device 12, a high-speed vortex airflow is formed in the pyrolysis furnace, so that the residence time of the phosphogypsum in the furnace is prolonged.

Further, a valve is provided on the communication pipeline between the tertiary air outlet of the kiln head cover of the rotary kiln 24 and the hot air inlet of the phosphogypsum pyrolysis device 12, so as to control the air volume through the valve.

Preferably, the phosphogypsum pyrolysis device 12 is a phosphogypsum cyclone-suspension separation type pyrolysis furnace, and the phosphogypsum pyrolysis device 12 is also provided with a pulverized coal inlet for adding pulverized coal. The present invention does not limit the number and position of the pulverized coal inlets, and those skilled in the art can set them according to actual needs.

Preferably, the phosphogypsum preheating device 11 is a multi-stage preheating device connected with multi-stage suspension preheaters. In some specific embodiments of the present invention, the number of preheaters is generally 4 (according to the company's desire to achieve The heat exchange effect determines the final number of stages), and they are connected in sequence. Each single-stage preheater and high temperature gas-solid separator 13 of the phosphogypsum preheating device 11 are low pressure loss type preheaters, such as cyclone preheaters. , Straight cylinder preheater, etc.

Preferably, the phosphogypsum pyrolysis acid production system 1 further includes: a phosphogypsum powder grinding and drying device 15, a phosphogypsum dry powder bin 16 and a dust collector 17; wherein the solid phase outlet of the phosphogypsum grinding and drying device 15 is connected to the phosphorus The gypsum dry powder bin 16 is connected, so that the phosphogypsum after grinding and drying is sent to the phosphogypsum dry powder bin 16; A part of the waste gas of the calcination system 2 is passed into the phosphogypsum powder grinding and drying device 15 through the pipeline, and the powder is selected while drying; the gas phase outlet of the phosphogypsum powder grinding and drying device 15 is connected with the gas phase inlet of the dust collector 17, The solid phase outlet of the dust collector 17 is connected to the phosphogypsum dry powder bin 16, so that the dust particles in the gas are collected by the dust collector 17 and sent to the phosphogypsum dry powder bin 16; the solid phase outlet of the phosphogypsum dry powder bin 16 is connected to the phosphogypsum dry powder bin 16. A thermal device 11 is connected to feed the phosphogypsum to the phosphogypsum preheating device 11 .

Further, the solid phase inlet of the gypsum powder grinding and drying device 15 is connected to the first belt conveyor, so that the phosphogypsum that has been fully dried and homogenized in the storage yard or the phosphogypsum that has been filtered and properly dispersed passes through the first belt conveyor. The belt conveyor is sent into the gypsum grinding and drying device 15 for grinding and drying. During this process, the phosphogypsum loses free water and crystal water and becomes hemihydrate gypsum. Furthermore, an iron remover is also installed on the first belt conveyor to prevent the iron material from damaging the grinding and drying machine 15 .

Further, a second belt conveyor is connected between the solid phase outlet of the gypsum grinding and drying device 15 and the phosphogypsum dry powder bin 16, so that the phosphogypsum is ground, dried and selected by the gypsum grinding and drying device 15 and then passed through the second belt conveyor. The belt conveyor is sent to the dry powder bin 16 for storage.

Furthermore, a first weighing scale is also provided between the second belt conveyor and the phosphogypsum dry powder bin 16, and a second weighing scale is also provided between the dust collector 17 and the phosphogypsum dry powder bin 16, and the materials are respectively weighed by the first weighing scale. After weighing with the second weighing scale, it enters the phosphogypsum dry powder bin 16 .

Further, between the phosphogypsum dry powder bin 16 and the phosphogypsum preheating device 11, a third weighing scale, a third belt conveyor and a hoist 18 are arranged in sequence, and the phosphogypsum dry powder bin 16 is unloaded after being measured by the third weighing scale. The third belt conveyor enters the ascending pipeline of the phosphogypsum preheating device 11 through the elevator 18 .

Further, the phosphogypsum powder grinding and drying device 15 is one of a hammer dryer, a vertical mill dryer, a vertical roller mill dryer, a disc mill dryer or a DMC mill dryer.

Preferably, a heat exchange cooling tower 19 is also connected between the phosphogypsum preheating device 11 and the acid making device 14, so that the waste gas containing high concentration SO ₂ enters the heat exchange cooling tower 19 after being collected by the phosphogypsum preheating device 11, and is cooled After that, sulfuric acid is obtained in the acid making unit.

Further, the heat exchange cooling tower 19 has the functions of both heat exchange and continuous cooling of the gas, and a small amount of dilute sulfuric acid can be sprayed in the tower, and the mineral dust and impurities in the gas can be washed away by the dilute sulfuric acid.

Preferably, the raw meal preheating device 21 is a multi-stage preheating device connected with multi-stage suspension preheaters. In some specific embodiments of the present invention, the number of preheaters is generally 4 (according to the company's desire to achieve The heat exchange effect determines the final number of stages), and are connected in sequence. Each single-stage preheater of the raw meal preheating device 21 and the enlarged gas-solid separator 22 are low pressure loss type preheaters, such as cyclone preheating. heater, straight cylinder preheater, etc.

Preferably, the mixing device 23 is newly installed through design calculation according to the production line. For example, the decomposition furnace of the original production line was transformed into a pyrolysis furnace for the pyrolysis of phosphogypsum, and a mixing device was added to mix the hot raw meal supplied by each system. The corresponding mixing device can be a tubular, spouted or spout-swirl combined furnace-type structure.

Preferably, the mixing device 23 is reconstructed from the decomposition furnace of the existing clinker production line. For example, it can be transformed from DD type, DD-I type, DD-II type, TDF type, TSD type, NFC type, MFC type decomposition furnace, etc. The temperature in the furnace is 860℃-920℃; it can be adjusted appropriately during the transformation The position and angle of the calciner pulverized coal and raw meal (including hot new calcium powder) entering the mixing device 23, cancel the tertiary air duct, and set the path of the flue gas in the smoke chamber (rising flue) unchanged.

In some specific embodiments of the present invention, the cement clinker calcining system 2 is transformed from the original clinker burning system, and the original clinker burning system includes: a raw meal preheating device, a decomposition furnace and a rotary kiln; Including: cancel the tertiary air directly entering the precalciner of the raw clinker firing system, so that the tertiary air is connected to the hot air inlet of the phosphogypsum pyrolysis device 12; at the same time, the flue gas and materials out of the precalciner are more capable of expanding the gas-solid separation The flue gas generated by the rotary kiln 24 directly enters the mixing device 23 and is discharged from the raw meal preheating device 21 of the cement clinker calcining system 2. The flue gas is strictly prohibited from entering the phosphogypsum pyrolysis acid production system 1. The present invention directly utilizes the existing or discontinued cement production line to carry out rapid transformation, and realizes large-scale resource utilization of phosphogypsum in the shortest time. Whether it is a double-series or single-series kiln system, the carbon reduction rate of the clinker preparation system after the transformation is not less than 12%. And after the single-series kiln line is transformed into double-series, the output of the cement production line can be greatly increased, which can be as high as twice the original. It can be said that this process method has the advantages of small environmental pollution, low production cost, and good economic benefits. .

In some more specific embodiments of the present invention, the mixing device 23 is transformed from a decomposition furnace with a pre-burning furnace in the original clinker burning system, and the raw meal preheating device in the original clinker burning system includes: C1-C5 preheater. During reconstruction: the raw meal preheating device 21 uses the C1-C4 preheater of the raw meal preheating device in the original clinker sintering system, and the C5 preheater is changed to an enlarged gas-solid separator 22, and the pre-burning furnace 31 Newly added hot fresh calcium inlet, and the original tertiary air duct is rerouted to connect the phosphogypsum pyrolysis device 12. After the transformation, the hot new calcium obtained from the phosphogypsum pyrolysis acid production system 1 is introduced into the pre-burning furnace 31 through the hot new calcium inlet, and enters the pre-burning furnace 31 together with the original C4 incoming material, and the mixed hot raw material is then used by the pre-burning furnace. The furnace 31 enters the main furnace 32 of the original decomposition furnace, and then enters the enlarged gas-solid separator 22 for gas-solid separation after exiting the main furnace 32 of the decomposition furnace. The separated powder enters the rotary kiln 24 for calcination.

In some more specific embodiments of the present invention, the mixing device 23 is transformed from the spouting type decomposition furnace in the original clinker burning system, and the raw meal preheating device in the original clinker burning system includes C1- C5 preheater. During the renovation: the raw meal preheating device 21 uses the C1-C4 preheater of the raw meal preheating device in the original clinker sintering system, and the C5 preheater is changed to an enlarged gas-solid separator 22 and a new decomposition furnace 41. The heat-increasing state new calcium hot state inlet and the original tertiary air duct are rerouted to connect the phosphogypsum pyrolysis device 12 . After the transformation, the hot new calcium obtained from the phosphogypsum pyrolysis acid-making system 1 is directly introduced into the decomposition furnace 41 (now the mixing device 23) through the hot state inlet of the hot new calcium, and the incoming C4 material passes through the raw meal of the original clinker system. The entrance enters, that is, the hot new calcium from the pyrolysis of phosphogypsum enters the decomposition furnace 41 (now the mixing device 23) together with the original C4 incoming material, and enters the enlarged gas-solid separator 22 after exiting the decomposition furnace 41 (the current mixing device 23). Gas-solid separation is performed, and the separated powder enters the rotary kiln 24 for calcination.

In some more specific embodiments of the present invention, the mixing device 23 is transformed from a spray-rotation combined type decomposition furnace in the original clinker burning system, and the raw meal preheating device in the original clinker burning system includes C1A -C5A preheater and C1B-C5B preheater. During reconstruction: The phosphogypsum preheating device 11 uses the C1B-C4B preheaters of the B series in the original clinker firing system, and the original C5B preheater is upgraded to a high-temperature gas-solid separator 13, which separates the high-temperature gas-solid from the high-temperature gas-solid separator. The hot new calcium from the boiler 13 directly enters the cone of the mixing device 23 in the original clinker firing system, which was upgraded from the original decomposition furnace, and the material from the original B series C4B feeding port enters the additional phosphogypsum pyrolysis device 12 ; The raw meal preheating device 21 uses the C1A-C4A preheater in the original clinker firing system to change the C5A preheater of the A series in the clinker firing system to the enlarged gas-solid separator 22, the original The tertiary air pipe is redirected to connect the hot air inlet of the phosphogypsum pyrolysis device 12 . The hot fresh calcium obtained from the modified phosphogypsum pyrolysis acid production system 1 of series B and the C4A incoming material of the original A series enter the mixing device 23 upgraded from the original decomposition furnace together, and then enter the expansion after exiting the mixing device 23. In the gas-solid separator 22, the separated powder enters the rotary kiln for calcination and is cooled by a grate cooler to prepare clinker.

Preferably, the cement clinker calcining system 2 further includes a grate cooler 25, and the solid phase inlet of the grate cooler 25 is connected with the solid phase outlet of the rotary kiln 24, so as to cool the fired clinker.

As a preferred technical solution of the present invention, the above-mentioned separate dual system for preparing sulfuric acid co-production cement from phosphogypsum includes: a system 1 for producing acid by pyrolysis of phosphogypsum and a system 2 for calcining cement clinker. in,

Phosphogypsum pyrolysis acid production system 1 includes: phosphogypsum preheating device 11, phosphogypsum pyrolysis device 12, high temperature gas-solid separator 13, acid production device 14, phosphogypsum powder grinding and drying device 15, phosphogypsum dry powder bin 16 With the dust collector 17, the solid phase outlet of the phosphogypsum powder grinding and drying device 15 is connected with the phosphogypsum dry powder bin 16, and the gas phase outlet of the phosphogypsum grinding and drying device 15 is connected with the gas phase inlet of the dust collector 17, and the dust collector The solid phase outlet of 17 is connected to the phosphogypsum dry powder bin 16, the solid phase outlet of the phosphogypsum dry powder bin 16 is connected to the phosphogypsum preheating device 11, and the solid phase outlet of the phosphogypsum preheating device 11 is connected to the solid phase outlet of the phosphogypsum pyrolysis device 12. The phase inlet is connected, the material outlet of the phosphogypsum pyrolysis device 12 is connected with the material inlet of the high-temperature gas-solid separator 13, the gas-phase outlet of the high-temperature gas-solid separator 13 is connected with the gas-phase inlet of the phosphogypsum preheating device 11, and the phosphogypsum is preheated. The gas-phase outlet of the device 11 is connected with the gas-phase inlet of the acid-making device 14;

The cement clinker calcining system 2 includes a raw meal preheating device 21, an enlarged gas-solid separator 22, a mixing device 23, a rotary kiln 24 and a grate cooler 25. The solid phase inlet of the mixing device 23 is respectively connected to the raw meal preheating device 21. The solid phase outlet of the high temperature gas-solid separator 13 is connected to the solid phase outlet of the high temperature gas-solid separator 13, the material outlet of the mixing device 23 is connected to the material inlet of the enlarged gas-solid separator 22, and the gas-phase outlet of the enlarged gas-solid separator 22 is connected to the raw material preheater. The gas phase inlet of the heating device 21 is connected, the solid phase outlet of the enlarged gas-solid separator 22 is connected with the material inlet of the rotary kiln 24, the solid phase outlet of the rotary kiln 24 is connected with the solid phase inlet of the grate cooler 25, and the solid phase outlet of the rotary kiln 24 is connected. The flue gas outlet is connected to the gas phase inlet of the mixing device 23, the tertiary air outlet of the kiln head cover of the rotary kiln 24 is connected to the hot air inlet of the phosphogypsum pyrolysis device 12, and the gas phase outlet of the raw meal preheating device 21 is connected to the phosphogypsum powder grinding and drying The gas phase inlet of the drying device 15 is connected.

In the present invention, a fan can be arranged on each gas connection pipeline as required.

A second aspect of the present invention provides a process for preparing sulfuric acid co-production cement from phosphogypsum, comprising the following steps:

Phosphogypsum pyrolysis for acid production: phosphogypsum conducts gas-solid two-phase heat exchange in the phosphogypsum preheating device 11, and then enters the phosphogypsum pyrolysis device 12 for pyrolysis reaction after preheating to above 800 °C, and enters the high-temperature gas-solid after the reaction is complete. The gas-solid separation is carried out in the separator 13, and the generated hot new calcium enters the mixing device 23, and the waste gas containing high concentration SO ₂ is collected by the phosphogypsum preheating device 11, and sulfuric acid is obtained in the acid making device;

Cement clinker calcination: the raw meal passes through the raw meal preheating device 21 for heat exchange, and then is mixed with the hot new calcium obtained by the pyrolysis of phosphogypsum in the mixing device 23, and the mixed material is in the enlarged gas-solid separator 22. After separation, the solid phase material enters the rotary kiln 24 for calcination to obtain cement clinker.

The present invention does not limit the specific composition of phosphogypsum, including dihydrate, hemihydrate and anhydrous phosphogypsum produced by industrial production methods of wet phosphoric acid (dihydrate method, hemihydrate method and anhydrous method) and pretreated phosphogypsum. Phosphogypsum, those skilled in the art can choose according to the actual situation. In some specific embodiments of the present invention, the selected chemical composition of phosphogypsum is: CaO 26%-36%, SO ₃ 36%-50%, SiO ₂ 2%-10%, P ₂ O ₅ 0.01%-2.5 %, F 0%-3%, K ₂ O 0%-0.7%, Na ₂ O 0%-0.5%, Al ₂ O ₃ 0%-1.4%, Fe ₂ O ₃ 0%-0.6%, MgO 0%-0.35 %, other 20%-24%.

Further, the percentage content of CaSO ₄ ·2H ₂ O in the phosphogypsum after grinding and drying is above 80%, and the sieve residue of the sieve with particle size of 80 μm in the calciner is controlled to be no more than 18%.

Preferably, the internal temperature of the phosphogypsum pyrolysis device 12 is 1000°C-1250°C. The air required for the pyrolysis reaction is provided by the tertiary air at the kiln head, and the tertiary air enters the phosphogypsum pyrolysis device 12 from the bottom and the side cone of the phosphogypsum pyrolysis device 12 respectively, and forms a high-speed vortex in the phosphogypsum pyrolysis device 12. The airflow controls the pyrolysis temperature and makes the phosphogypsum stay in the phosphogypsum pyrolysis device 12 enough to make the phosphogypsum fully pyrolyzed.

Preferably, in the process of making acid by pyrolysis of phosphogypsum, the coal powder used is at least one of bituminous coal, anthracite and lignite, and the calorific value is in the range of 4000-8000 kcal/kg.

Further, the input amount of pulverized coal is calculated according to the carbon-sulfur ratio of 1.1-2.0, and the decomposition rate of phosphogypsum is above 90% within this ratio range.

Preferably, the waste gas containing high concentration SO ₂ is collected by the phosphogypsum preheating device 11 , and cooled by the heat exchange cooling tower 19 to obtain sulfuric acid in the acid making device 14 .

Preferably, after the solid phase material enters the rotary kiln 24 for calcination, it is cooled by the grate cooler 25 to obtain cement clinker.

Preferably, cement clinker is ground with gypsum and admixture to obtain qualified cement.

Example 1

The phosphogypsum raw material used in Example 1 of the present invention comes from a company in Guizhou, and the percentage content of CaSO ₄ ·2H ₂ O is 93.75%, and its main composition is shown in Table 1.

Table 1

Element CaO SO₃ SiO₂ P₂O₅ F K₂O Na₂O Al₂O₃ Fe₂O₃ MgO Loss Phosphogypsum 31.35 42.40 2.78 0.97 0.12 0.07 0.44 0.37 0.14 0.07 21.29

A separate dual system for preparing sulfuric acid co-production cement with phosphogypsum, as shown in Figure 1, includes: a phosphogypsum pyrolysis acid-making system 1 and a cement clinker calcining system 2. Phosphogypsum pyrolysis acid production system 1 includes: phosphogypsum preheating device 11, phosphogypsum pyrolysis device 12, high temperature gas-solid separator 13, acid production device 14, phosphogypsum powder grinding and drying device 15, phosphogypsum dry powder bin 16 , dust collector 17, elevator 18 and heat exchange cooling tower 19. The cement clinker calcining system 2 includes a raw meal preheating device 21 , an enlarged gas-solid separator 22 , a mixing device 23 refitted from the original decomposition furnace with a pre-burning furnace, a rotary kiln 24 and a grate cooler 25 . The solid phase inlet of the phosphogypsum powder grinding and drying device 15 is connected to the first belt conveyor, and an iron remover is also installed on the first belt conveyor; The two belt conveyors are connected, and a first weighing scale is also arranged between the second belt conveyor and the phosphogypsum dry powder bin 16; the gas phase outlet of the phosphogypsum powder grinding and drying device 15 is connected with the gas phase inlet of the dust collector 17, and the dust collector The solid phase outlet of 17 is connected with the phosphogypsum dry powder warehouse 16, and a second weighing scale is also provided between the dust collector 17 and the phosphogypsum dry powder warehouse 16; the solid phase outlet of the phosphogypsum dry powder warehouse 16 is connected with the phosphogypsum preheating device 11, A third weighing scale, a third belt conveyor and an elevator 18 are arranged between the phosphogypsum dry powder bin 16 and the phosphogypsum preheating device 11 in sequence; the solid phase outlet of the phosphogypsum preheating device 11 and the solid phase outlet of the phosphogypsum pyrolysis device 12 The inlet is connected, the material outlet of the phosphogypsum pyrolysis device 12 is connected with the material inlet of the high-temperature gas-solid separator 13, the gas-phase outlet of the high-temperature gas-solid separator 13 is connected with the gas-phase inlet of the phosphogypsum preheating device 11, and the phosphogypsum preheating device The gas phase outlet of 11 is connected with the gas phase inlet of the acid making device 14, and a heat exchange cooling tower 19 is also connected between the phosphogypsum preheating device 11 and the acid making device 14; the solid phase inlet of the mixing device 23 is respectively connected with the raw material preheating device. The solid phase outlet of 21 is connected to the solid phase outlet of the high-temperature gas-solid separator 13, the material outlet of the mixing device 23 is connected to the material inlet of the enlarged gas-solid separator 22, and the gas-phase outlet of the enlarged gas-solid separator 22 is connected to the raw material. The gas phase inlet of the preheating device 21 is connected, the solid phase outlet of the enlarged gas-solid separator 22 is connected with the material inlet of the rotary kiln 24, the solid phase outlet of the rotary kiln 24 is connected with the solid phase inlet of the grate cooler 25, and the rotary kiln 24 The outlet of the flue gas is connected to the gas phase inlet of the mixing device 23, the tertiary air outlet of the kiln head cover of the rotary kiln 24 is connected to the hot air inlet of the phosphogypsum pyrolysis device 12, and the hot air inlet of the phosphogypsum pyrolysis device 12 is set at the phosphogypsum thermal Valves are provided on the bottom and side cones of the pyrolysis device 12, the tertiary air outlet of the kiln head cover of the rotary kiln 24 and the hot air inlet of the phosphogypsum pyrolysis device 12 are provided with valves, and the gas phase outlet of the raw meal preheating device 21 is connected to The gas phase inlet of the phosphogypsum powder grinding and drying device 15 is connected.

Retrofit method: retrofit a 2500t/d new dry process cement clinker production line (see Figure 2). During reconstruction: ①Add all equipment and equipment of the phosphogypsum pyrolysis acid production system, including phosphogypsum preheating device 11, phosphogypsum pyrolysis device 12, high temperature gas-solid separator 13, acid production device 14, phosphogypsum powder grinding and drying Drying device 15, phosphogypsum dry powder bin 16, dust collector 17, elevator 18, heat exchange cooling tower 19, etc. ②The original cement clinker calcining system was transformed, including changing the C5 cyclone into an enlarged gas-solid separator 22, and adding a hot fresh calcium inlet to the pre-burning furnace 31 (that is, the function of the original decomposition furnace with a pre-burning furnace). It was changed to a mixing device 23), and the original tertiary air pipe was diverted to connect the phosphogypsum pyrolysis device 12. After the transformation, the hot new calcium obtained from the phosphogypsum pyrolysis acid production system is introduced into the pre-burning furnace 31 through the hot new calcium inlet, and enters the pre-burning furnace 31 together with the original C4 incoming material, and the mixed hot raw material is then sent to the pre-burning furnace. 31 enters the main furnace 32 of the original decomposition furnace, and after leaving the main furnace 32 of the decomposition furnace, it enters the enlarged gas-solid separator 22 for gas-solid separation, and the separated powder enters the rotary kiln 24 for calcination and is cooled by the grate cooler 25. out clinker.

The specific production method is as follows: the aged phosphogypsum is fully dried and homogenized in the storage yard, and then sent to the grinding and drying device 15 through the first belt conveyor for grinding and drying, and the free water in the phosphogypsum is removed. An iron remover is installed on the belt conveyor to prevent iron materials from damaging the grinding and drying machine 15; part of the waste gas from the clinker sintering system (the temperature is controlled at 300-350°C) is passed into the grinding and drying machine 15 through the pipeline. Powder selection is carried out at the same time as drying, and the particle size of the material is controlled at 10 μm-80 μm. The phosphogypsum after powder selection is weighed by the first weighing scale and then sent to the phosphogypsum dry powder bin 16, and the dust-containing particles in the gas are collected by the dust collector 17. Collected and weighed by the second weighing scale and then sent to the phosphogypsum dry powder bin 16; the dry powder bin 16 is unloaded by the third weighing scale and then fed to the third belt conveyor, and then enters the phosphogypsum preheating device through the elevator 18 11, the phosphogypsum enters the phosphogypsum preheating device 11, and the phosphogypsum conducts gas-solid two-phase heat exchange in the phosphogypsum preheating device 11, and then enters the phosphogypsum swirling-suspended state after preheating to 800-900 °C In the separation type pyrolysis furnace 12, the phosphogypsum cyclone-suspended state separation type pyrolysis furnace 12 uses tertiary air to enter the phosphogypsum cyclone-suspended state separation type pyrolysis furnace 12 from the vertical upward of the furnace bottom and tangentially from the side of the cone part respectively. , the phosphogypsum cyclone-suspended separation type pyrolysis furnace 12 produces a cyclone-spray combined type upward flow field, and the coal powder and phosphogypsum powder are dispersed with the tertiary air to complete full mixing, combustion and pyrolysis. Because phosphogypsum pyrolysis requires a reducing atmosphere, the combustion atmosphere is controlled by controlling the air volume and carbon-sulfur ratio, and at the same time, the temperature of the high-temperature oxidation zone of the phosphogypsum pyrolysis furnace is guaranteed to be 1000-1250 ° C, and the decomposition rate of phosphogypsum is controlled to about 92%. After fully pyrolyzed, enter the high-temperature gas-solid separator 13 with the hot air flow to carry out gas-solid separation, and the solid powder obtained after separation—hot state new calcium enters the pre-burning furnace 31 (now mixing device 23) of the original decomposition furnace, After pre-mixing with the material in the pre-combustion furnace 31, it enters the rotary kiln 24 through the main furnace 32 of the decomposition furnace (now the mixing device 23) and the enlarged gas-solid separator 22 for calcination, and the calcined clinker is cooled by the grate cooler 25. Qualified clinker; waste gas containing SO ₂ (concentration 8-11%, temperature at 300-400 ℃) is collected at the exhaust gas outlet of the phosphogypsum preheating device 11 and enters the heat exchange cooling tower 19, after cooling to 20-40 ℃ Sulfuric acid is obtained in the acid plant. Bituminous coal is selected as the fuel used in the phosphogypsum cyclone-suspended separation pyrolysis furnace 12, the carbon-sulfur ratio is selected as 1.25, and the calorific value is 5500kcal/kg-6000kcal/kg. After the transformation, the clinker production capacity is increased to about 4500t/d.

Example 2

A kind of separation type dual system and production method for preparing sulfuric acid co-production cement with phosphogypsum, the difference between it and embodiment 1 is:

The adopted phosphogypsum raw material comes from a company in Guizhou, the percentage content of CaSO ₄ ·0.5H ₂ O is 93.23%, and its main composition is shown in Table 2.

Table 2

Element CaO SO₃ SiO₂ P₂O₅ F K₂O Na₂O Al₂O₃ Fe₂O₃ MgO Loss Phosphogypsum 33.04 44.30 2.09 1.05 0.46 0.059 0.21 0.27 0.10 0.051 18.37

Modification method: Modification of a 2000t/d new dry process cement clinker production line (see Figure 3), the decomposition furnace is a spouting type decomposition furnace, and the size of the decomposition furnace is Φ4.52×22.7m. During the renovation: ①Add all equipment and equipment of the phosphogypsum pyrolysis acid production system, including phosphogypsum preheating device 11, phosphogypsum pyrolysis device 12, high temperature gas-solid separator 13, acid production device 14, phosphogypsum powder grinding and drying Drying device 15, phosphogypsum dry powder bin 16, dust collector 17, elevator 18, heat exchange cooling tower 19, etc. ②The original cement clinker calcining system was transformed, including changing the C5 cyclone into an enlarged gas-solid separator 22, adding a new thermal calcium inlet to the decomposition furnace 41, and diverting the original tertiary air duct to connect the phosphogypsum pyrolysis device 12. After the transformation, the hot new calcium obtained from the phosphogypsum pyrolysis acid production system 1 is directly introduced into the decomposition furnace 41 (now the mixing device 23) through the hot state new calcium inlet, that is, it enters the mixing device 23 together with the original C4 incoming material, and is discharged out. After the mixing device 23 enters the enlarged gas-solid separator 22 for gas-solid separation, the separated powder enters the rotary kiln 24 for calcination and is cooled by the grate cooler 25 to prepare clinker.

The specific production method is as follows: the thermal decomposition temperature of the pyrolysis furnace is 1150-1200 ° C in the high temperature oxidation zone, the decomposition rate of phosphogypsum is about 95%, and after the reaction is completed, the hot air flow enters the high temperature gas-solid separator 13 for gas-solid separation, and after separation The obtained solid powder-hot new calcium directly enters the original decomposition furnace 41 (the current mixing device 23), and is mixed with the incoming material of the cement clinker calcining system 2 in the mixing device 23 and passes through the enlarged gas-solid separator 22. It enters the rotary kiln 24 for calcination, and the calcined clinker is cooled by the grate cooler 25 to obtain qualified clinker _; the waste gas containing 8-11% SO2 (temperature at 350-400°C) is heated in the phosphogypsum preheating device 11 The waste gas is collected from the outlet and enters the heat exchange cooling tower 19, and after cooling to 20-40 °C, sulfuric acid is obtained in the acid production workshop. Bituminous coal is selected as the fuel used in the phosphogypsum cyclone-suspended separation pyrolysis device 12, with a calorific value of 5500kcal/kg-6000kcal/kg, and a carbon-sulfur ratio of 1.25. After the transformation, the clinker production capacity is increased from the original 2000t/d to about 4000t/d.

Example 3

A kind of separation type dual system and production method for preparing sulfuric acid co-production cement with phosphogypsum, the difference between it and embodiment 1 is:

The adopted phosphogypsum raw material comes from a company in Yunnan, and the percentage content of CaSO ₄ ·2H ₂ O is 90.15%, and its main composition is shown in Table 3.

table 3

Element CaO SO₃ SiO₂ P₂O₅ F K₂O Na₂O Al₂O₃ Fe₂O₃ MgO Loss Phosphogypsum 30.13 41.70 7.78 0.06 0.02 0.07 0.04 0.12 0.04 0.03 20.01

Renovation method: Renovate a 5000t/d new dry process cement clinker production line in a high altitude area (see Figure 4). During renovation: ①Add some equipment of phosphogypsum pyrolysis acid production system, mainly including phosphogypsum pyrolysis device 12, high temperature gas-solid separator 13, acid production device 14, phosphogypsum powder grinding and drying device 15, phosphogypsum dry powder silo 16. Dust collector 17, elevator 18 and heat exchange cooling tower 19; among them, the phosphogypsum preheating device 11 uses C1B-C4B of the original production line B series, and the C5B cyclone of the original B series is upgraded to high temperature gas Solid separator 13, the hot new calcium from the high temperature gas-solid separator 13 directly enters the conical part of the decomposition furnace 51 (now the mixing device 23), and other cement raw materials enter the decomposition furnace 51 through the original C4A feeding port (now mixed device 23). ②The original cement clinker calcining system was transformed, including changing the A-series C5A cyclone to an enlarged gas-solid separator 22, and the original tertiary air duct was rerouted to connect the phosphogypsum pyrolysis device to the phosphogypsum pyrolysis acid-making system 12. After the transformation, the hot new calcium obtained from the phosphogypsum pyrolysis acid-making system and the C4A incoming material of the original A series enter the decomposition furnace 51 (now the mixing device 23), and then enter the expansion furnace 51 (now the mixing device 23) In the gas-solid separator 22, the separated powder enters the rotary kiln 24 for calcination and is cooled by the grate cooler 25 to prepare clinker.

The specific production method is as follows: the fuel used in the phosphogypsum cyclone-suspended separation pyrolysis device 12 is bituminous coal and lignite, the calorific value of bituminous coal is 6000kcal/kg-6500kcal/kg, and the calorific value of lignite is 4000kcal/kg-4500kcal/kg kg, bituminous coal and lignite are divided into two coal injection pipes into the phosphogypsum pyrolysis furnace according to the mass ratio of 7:3 and the carbon-sulfur ratio of 1.25. The lignite coal injection pipe is above the tertiary air, and the bituminous coal injection pipe is on the opposite side of the lignite coal injection pipe. The flammable lignite can burn quickly in high altitude areas and increase the temperature in the initial section of the phosphogypsum pyrolysis furnace, making it comparable to single use. It ignites faster than bituminous coal. However, the rapid combustion of lignite also consumes a large amount of oxygen in the limited space, so that the initial combustion speed of bituminous coal is suppressed, and then the combustion speed is gradually accelerated with the full mixing of bituminous coal and tertiary air, which makes the temperature distribution of the phosphogypsum pyrolysis furnace more balanced. , in the pyrolysis furnace thermal decomposition temperature high temperature oxidation zone is 1150-1200 ℃, the decomposition rate of phosphogypsum is not less than 92%, after the reaction is complete, the hot air flow enters the high temperature gas-solid separator 13 for gas-solid separation, containing 8- The waste gas of 10% SO ₂ (temperature at 300-400°C) is collected at the waste gas outlet of the phosphogypsum preheating device 11 and enters the heat exchange cooling tower 19. After cooling to 20-40°C, sulfuric acid is obtained in the acid production workshop. After the transformation, the production capacity of clinker has been increased to more than 6000t/d.

Compared with the prior art, the beneficial effects of the present invention also include:

The traditional phosphogypsum co-production cement process is to mix phosphogypsum calcareous raw materials and limestone calcareous raw materials together. Because the pyrolysis temperature of phosphogypsum is too high, the limestone calcareous raw materials and other raw materials such as clay appear too early in liquid phase. In order to solve this problem, the present invention separates phosphogypsum and other raw materials for reaction by setting up a separate phosphogypsum pyrolysis device. The phosphogypsum is pyrolyzed and the clinker is calcined in a pyrolysis environment of about 1200°C. According to the existing cement process, it is completed in a rotary kiln to avoid excessive liquid phase in the raw meal.

The invention separates the phosphogypsum pyrolysis acid-making process that needs to be realized in a reducing atmosphere and the cement clinker calcining process that needs to be realized under an oxidizing atmosphere (or a weak reducing atmosphere), and the high-concentration SO2 produced by the acid _- making system passes through The phosphogypsum preheating device set in the phosphogypsum pyrolysis acid production system exchanges heat and enters the acid production device to complete acid production; the hot new calcium generated by the phosphogypsum pyrolysis acid production system enters the mixing device, and is preheated by the raw meal preheating device. The raw meal powder obtained by heat is mixed evenly and enters the rotary kiln to complete the clinker calcination. The flue gas generated by the cement clinker calcining system passes through the raw meal preheating device set in the cement clinker calcining system and then enters the waste heat power generation or raw meal after heat exchange. grind.

Compared with the traditional phosphogypsum acid-making system, the newly added important thermal equipment of the phosphogypsum pyrolysis acid-making system of the invention is a reducing atmosphere. The working phosphogypsum pyrolysis device and high temperature gas-solid separator; compared with the traditional clinker calcining system, the new important thermal equipment of the cement clinker calcining system of the present invention is an oxidizing atmosphere (or a weak reducing atmosphere) The mixing device (which can be improved on the basis of the original calciner or can be newly set up separately) and the enlarged gas-solid separator; the separated dual system of the present invention can realize the rapid upgrading and transformation of the existing new dry process cement production line , Co-processing phosphogypsum while increasing the output of the original production line.

The invention can rapidly transform the existing cement sintering system, realizes acid production from phosphogypsum without affecting the production of cement clinker, and has room for increasing production and efficiency for a single series of old cement production lines; The decomposition rate of phosphogypsum can reach more than 90%, and the SO ₂ concentration in the flue gas is not less than 8%, which can realize the large-scale and high-efficiency development and utilization of phosphogypsum, and solve the huge pollution problem caused by the current accumulation of phosphogypsum.

The specific embodiments of the present invention described above do not limit the protection scope of the present invention. Any other corresponding changes and modifications made according to the technical concept of the present invention shall be included in the protection scope of the claims of the present invention.

Claims (10)

1. a separate dual system for preparing sulfuric acid co-production cement with phosphogypsum, is characterized in that: comprise phosphogypsum pyrolysis acid-making system and cement clinker calcining system; wherein, The phosphogypsum pyrolysis acid-making system includes: a phosphogypsum preheating device, a phosphogypsum pyrolysis device, a high-temperature gas-solid separator and an acid making device; the solid phase outlet of the phosphogypsum preheating device is connected to the phosphogypsum thermal device. The solid phase inlet of the pyrolysis device is connected, the material outlet of the phosphogypsum pyrolysis device is connected to the material inlet of the high-temperature gas-solid separator, and the gas-phase outlet of the high-temperature gas-solid separator is connected to the outlet of the phosphogypsum preheating device. The gas phase inlet is connected, and the gas phase outlet of the phosphogypsum preheating device is connected with the gas phase inlet of the acid making device; The cement clinker calcining system includes a raw meal preheating device, an enlarged gas-solid separator, a mixing device and a rotary kiln; the solid phase inlet of the mixing device is respectively connected with the solid phase outlet and the solid phase outlet of the raw meal preheating device. The solid phase outlet of the high temperature gas-solid separator is connected, the material outlet of the mixing device is connected to the material inlet of the enlarged gas-solid separator, and the solid phase outlet of the enlarged gas-solid separator is connected to the rotary kiln material inlet connection. 2. according to the described phosphogypsum of claim 1, the separation type dual system of preparing sulfuric acid co-production cement is characterized in that, the gas-phase outlet of the enlarged gas-solid separator is connected with the gas-phase inlet of the raw meal preheating device, so that the The flue gas outlet of the rotary kiln is connected to the gas phase inlet of the mixing device, and the tertiary air outlet of the kiln head cover of the rotary kiln is connected to the hot air inlet of the phosphogypsum pyrolysis device. 3. The separated dual system for preparing sulfuric acid co-production cement from phosphogypsum according to claim 2, wherein the hot air inlet of the phosphogypsum pyrolysis device is arranged at the bottom and the side cone of the phosphogypsum pyrolysis device A valve is provided on the communication pipeline between the tertiary air outlet of the rotary kiln hood and the hot air inlet of the phosphogypsum pyrolysis device. 4. The separated dual system for preparing sulfuric acid co-production cement from phosphogypsum according to claim 1, is characterized in that, the phosphogypsum pyrolysis acid-making system further comprises: a phosphogypsum powder grinding and drying device, a phosphogypsum dry powder bin and a Dust collectors; of which, The solid phase outlet of the phosphogypsum powder grinding and drying device is connected with the phosphogypsum dry powder bin, and the gas phase inlet of the phosphogypsum powder grinding and drying device is connected with the gas phase outlet of the raw meal preheating device. The gas phase outlet of the gypsum powder grinding and drying device is connected to the gas phase inlet of the dust collector, the solid phase outlet of the dust collector is connected to the phosphogypsum dry powder bin, and the solid phase outlet of the phosphogypsum dry powder bin is connected to the dust collector. The phosphogypsum preheating device is connected. 5. The separated dual system for preparing sulfuric acid co-production cement from phosphogypsum according to claim 1 is characterized in that, a heat exchange cooling tower is also connected between the phosphogypsum preheating device and the acid making device; The material calcining system further includes a grate cooler, the solid phase inlet of the grate cooler is connected with the solid phase outlet of the rotary kiln. 6. The separated dual system for preparing sulfuric acid co-production cement from phosphogypsum according to claim 1, wherein the phosphogypsum pyrolysis device is a phosphogypsum cyclone-suspended state separation type pyrolysis furnace, and the phosphogypsum pyrolysis device is a The preheating device is a multistage preheating device connected with multistage suspension preheaters, and each single stage preheater and the high temperature gas-solid separator of the phosphogypsum preheating device are low pressure loss type preheaters; The feed preheating device is a multi-stage preheating device connected with multi-stage suspension preheaters, and each single-stage preheater and the enlarged gas-solid separator of the raw meal preheating device are low pressure loss type preheaters. 7. The separation dual system for preparing sulfuric acid co-production cement from phosphogypsum according to claim 1 is characterized in that, the cement clinker calcining system is transformed from the original clinker calcining system, and the original clinker The firing system includes: a raw meal preheating device, a decomposition furnace and a rotary kiln; the transformation includes: canceling the tertiary air directly entering the decomposition furnace of the raw clinker firing system, so that the tertiary air is connected to the hot air inlet of the phosphogypsum pyrolysis device; At the same time, the flue gas and materials coming out of the decomposition furnace are separated in the enlarged gas-solid separator. 8. The separation dual system for preparing sulfuric acid co-production cement from phosphogypsum according to claim 7 is characterized in that, the mixing device is transformed from a decomposition furnace with a pre-burning furnace in the original clinker burning system, The raw meal preheating device in the original clinker sintering system includes C1-C5 preheaters; during the transformation: the raw meal preheating device uses the C1-C4 preheating of the raw meal preheating device in the original clinker sintering system The C5 preheater was changed to the enlarged gas-solid separator, the pre-burner added a new hot calcium inlet, and the original tertiary air duct was rerouted to connect the phosphogypsum pyrolysis device; Or, the mixing device is transformed from the spouting type decomposition furnace in the original clinker burning system, and the raw meal preheating device in the original clinker burning system includes C1-C5 preheaters; The raw meal preheating device uses the C1-C4 preheater of the raw meal preheating device in the original clinker sintering system, and the C5 preheater is changed to the enlarged gas-solid separator, and the decomposition furnace adds a new thermal state. Calcium hot state inlet, the original tertiary air duct is diverted to connect the phosphogypsum pyrolysis device; Or, the mixing device is transformed from the spray-rotation combined type decomposition furnace in the original clinker burning system, and the raw meal preheating device in the original clinker burning system includes C1A-C5A preheater and C1B-C5B preheater. Heater; during renovation: the phosphogypsum preheating device uses the C1B-C4B preheater of the B series in the original clinker firing system, and the original C5B preheater is upgraded and transformed into the high temperature gas-solid separator. The hot new calcium from the high-temperature gas-solid separator directly enters the cone of the mixing device in the original clinker sintering system, which was upgraded from the original decomposition furnace, and the material from the discharge port of the original B series C4B preheater enters The added phosphogypsum pyrolysis device; the raw meal preheating device uses the C1A-C4A preheater in the original clinker sintering system, and changes the C5A preheater of the A series in the clinker sintering system to The enlarged gas-solid separator and the original tertiary air pipe are rerouted to connect the hot air inlet of the phosphogypsum pyrolysis device. 9. The separation type dual system for preparing sulfuric acid co-production cement according to the described phosphogypsum of claim 1, is characterized in that, the separation type dual system for preparing sulfuric acid co-production cement from phosphogypsum comprises: phosphogypsum pyrolysis acid production system and Cement clinker calcination system; wherein, The phosphogypsum pyrolysis acid-making system includes: a phosphogypsum preheating device, a phosphogypsum pyrolysis device, a high-temperature gas-solid separator, an acid generating device, a phosphogypsum powder grinding and drying device, a phosphogypsum dry powder bin and a dust collector; The solid phase outlet of the phosphogypsum powder grinding and drying device is connected to the phosphogypsum dry powder bin, the gas phase outlet of the phosphogypsum powder grinding and drying device is connected to the gas phase inlet of the dust collector, and the dust collector The solid phase outlet of the phosphogypsum dry powder silo is connected to the phosphogypsum dry powder bin, the solid phase outlet of the phosphogypsum dry powder bin is connected to the phosphogypsum preheating device, and the solid phase outlet of the phosphogypsum preheating device is connected to the phosphogypsum heat sink. The solid phase inlet of the pyrolysis device is connected, the material outlet of the phosphogypsum pyrolysis device is connected to the material inlet of the high-temperature gas-solid separator, and the gas-phase outlet of the high-temperature gas-solid separator is connected to the outlet of the phosphogypsum preheating device. The gas phase inlet is connected, and the gas phase outlet of the phosphogypsum preheating device is connected with the gas phase inlet of the acid making device; The cement clinker calcining system includes a raw meal preheating device, an enlarged gas-solid separator, a mixing device, a rotary kiln and a grate cooler. The solid phase inlet of the mixing device is respectively connected with the solid phase inlet of the raw meal preheating device. The phase outlet is connected to the solid phase outlet of the high temperature gas-solid separator, the material outlet of the mixing device is connected to the material inlet of the enlarged gas-solid separator, and the gas phase outlet of the enlarged gas-solid separator is connected to the The gas phase inlet of the raw meal preheating device is connected, the solid phase outlet of the enlarged gas-solid separator is connected to the material inlet of the rotary kiln, and the solid phase outlet of the rotary kiln is connected to the solid phase outlet of the grate cooler. The inlet is connected, the flue gas outlet of the rotary kiln is connected with the gas phase inlet of the mixing device, the tertiary air outlet of the kiln head cover of the rotary kiln is connected with the hot air inlet of the phosphogypsum pyrolysis device, the raw meal The gas phase outlet of the preheating device is connected with the gas phase inlet of the phosphogypsum powder grinding and drying device. 10. a technique for preparing sulfuric acid co-production cement with phosphogypsum, is characterized in that, comprises the following steps: Phosphogypsum pyrolysis for acid production: phosphogypsum conducts gas-solid two-phase heat exchange in the phosphogypsum preheating device, and then enters the phosphogypsum pyrolysis device for pyrolysis reaction after preheating to above 800 °C. After the reaction is complete, it enters the Gas-solid separation is carried out in the high-temperature gas-solid separator, the generated hot fresh calcium enters the mixing device, the waste gas containing high concentration SO ₂ is collected by the phosphogypsum preheating device, and sulfuric acid is obtained in the acid-making device. ; The internal temperature of the phosphogypsum pyrolysis device is 1000°C-1250°C; in the process of making acid by pyrolysis of phosphogypsum, the pulverized coal used is at least one of bituminous coal, anthracite and lignite, and the calorific value ranges from 4000- 8000kcal/kg; the input amount of pulverized coal is calculated according to the carbon-sulfur ratio of 1.1-2.0; Cement clinker calcination: The raw meal passes through the raw meal preheating device to exchange heat, and then mixes with the hot new calcium obtained by pyrolysis of phosphogypsum in the mixing device. After the gas-solid separation is achieved, the solid phase material enters the rotary kiln for calcination to obtain cement clinker; The process for preparing sulfuric acid co-production cement from phosphogypsum is realized by a separate dual system for preparing sulfuric acid co-production cement from phosphogypsum according to any one of claims 1 to 9.

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