Process system for suspension calcination of dolomite

Abstract

The utility model discloses a process system for suspension calcination of dolomite, which relates to the field of dolomite calcination production systems, and is characterized in that a dolomite raw material is ground and homogenized, then enters a multi-stage cyclone preheater by means of a metering, conveying and lifting device, is mixed with next-stage hot flue gas for heat exchange, is subjected to gas-solid separation, is preheated to 600-800 DEG C, and then enters a calcining furnace; and decomposing at the temperature of 860-920 DEG C. And the calcined material and flue gas are subjected to gas-solid separation, enter a multi-stage cooling device, are gradually cooled to 50-100 DEG C through a cyclone cooler and a fluidization cooler, and are conveyed. In the whole process, the flue gas pipeline recovers waste heat, the oxygen-containing hot air pipeline participates in circulation, and the electric valves connected with the pipelines precisely control the flow directions of materials and gas.

Description

Technical Field

[0001] This utility model relates to the field of dolomite calcination production systems, specifically a process system for suspension calcination of dolomite. Background Technology

[0002] Dolomite is one of the important raw materials in the magnesium metal smelting industry. Magnesium metal can be widely used in industrial manufacturing, transportation, construction, military and other industries. The production process of magnesium metal can generally be divided into several steps, including dolomite calcination, grinding and briquetting, calcination reduction and refining. Calcination of dolomite into calcined white dolomite is an important step in the preceding production process, and the quality of the finished calcined dolomite directly affects the quality of subsequent magnesium metal products.

[0003] Traditional dolomite calcination employs a technique combining preheating and pre-decomposition in a vertical kiln with complete decomposition in a rotary kiln. The main calcination process involves preheating and pre-decomposing the dolomite in the vertical kiln, followed by complete decomposition in the rotary kiln. However, vertical kiln calcination is not suitable only for calcining lumpy materials and faces various challenges, including low heat and mass transfer rates, low decomposition reaction rates, high calcination temperatures, high energy consumption, uneven product quality, and high production costs.

[0004] The novel suspension calcination technology for dolomite was developed to solve these problems. Compared with traditional calcination methods, suspension calcination can calcine powdery materials, has a high decomposition rate during the calcination process, and the decomposed products have high hydration activity. It reduces the occurrence of under-calcination and over-calcination during the dolomite calcination process. Compared with traditional calcination methods, it has many advantages and is the preferred technology for future dolomite calcination processes. Utility Model Content

[0005] The purpose of this invention is to provide a process system for calcining dolomite in suspension. The system involves mixing and exchanging heat with the next stage of hot flue gas through a multi-stage cyclone preheater, followed by gas-solid separation. After being preheated to 600℃-800℃, the flue gas enters the calcination furnace and decomposes at 860℃-920℃. The calcined material and flue gas then undergo gas-solid separation before entering a multi-stage cooling device. This system aims to solve the problems existing in the current dolomite calcination production process, such as low heat and mass transfer efficiency, high energy consumption per unit product, uneven product quality, and high production costs.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A process system for calcining dolomite in suspension includes multiple rows of multi-stage preheating devices, a calcining furnace, and a multi-stage cooling device. The multi-stage preheating device is characterized by comprising one or more sets of cyclone preheaters, with each stage connected sequentially to the next stage cyclone preheater, up to the penultimate stage. The penultimate stage cyclone preheater is connected to the inlet of the calcining furnace. The calcining furnace contains multiple sets of burners. The outlet of the calcining furnace is connected to the last stage cyclone preheater for gas-solid separation, and then connected to the multi-stage cooling device. The multi-stage cooling device includes cyclone coolers and fluidized bed coolers. Both the first and last stage cooling devices employ cyclone coolers, and fluidized bed coolers are connected between the cyclone coolers.

[0008] The top of the calcining furnace is equipped with a flue gas pipeline, which connects sequentially from the last stage cyclone preheater to the first stage cyclone preheater, and finally from the first stage cyclone preheater to the waste heat recovery device.

[0009] The multi-stage cooling device is equipped with oxygen-containing hot air pipes, which are connected sequentially. The first-stage cooling device is connected to the calcining furnace, and the last-stage cooling device is connected to an external dust collection device.

[0010] Both the final stage cooling device and the fluidized cooler are equipped with discharge pipes, and the finished product discharge pipes are connected to the finished product conveying device.

[0011] The cooling temperature of the finished material sent to the finished product conveying device is 50℃-100℃.

[0012] The calcination temperature of the calcining furnace is 860℃-920℃.

[0013] The material preheating temperature is 600℃-800℃.

[0014] Electric valves are installed between each connecting pipe.

[0015] After grinding and homogenization, the raw dolomite is fed into the first-stage cyclone preheater via metering, conveying, and lifting devices. In each stage of the cyclone preheater, the cold material is sequentially mixed and heat-exchanged with hot flue gas from the next stage, undergoing gas-solid separation and gradually preheated to 600℃-800℃ before entering the calcination furnace. Inside the calcination furnace, fuel is injected into the bottom burner for combustion, maintaining the calcination temperature at 860℃-920℃, promoting complete decomposition of the raw dolomite. The calcined material and flue gas then enter the final stage cyclone preheater for gas-solid separation, after which the material enters a multi-stage cooling system. In the multi-stage cooling system, the first-stage cyclone cooler provides initial cooling for small-diameter materials, followed by further cooling in a fluidized bed cooler. Some of the cooled finished material is directly discharged to the finished product conveying device, while some continues into subsequent cyclone coolers and fluidized bed coolers, ultimately cooling the finished material to 50℃-100℃ before being conveyed out. Throughout the process, waste heat is recovered from the flue gas pipeline, oxygen-containing hot air pipelines participate in the circulation, and electric valves between the connecting pipelines control the flow of materials and gases.

[0016] Compared with the prior art, the beneficial effects of this utility model are:

[0017] This invention relates to a method where dolomite material is preheated and decomposed before being calcined in a kiln. This process ensures sufficient contact between the gas and solid phases, resulting in rapid heat and mass transfer and a fast calcination reaction. This significantly increases the dolomite content and reduces under-burning and over-burning.

[0018] This invention features a calcining kiln with uniform internal temperature, atmosphere, and concentration distribution; adjustable calcination time and atmosphere; and complete material reaction. The resulting calcined white material is of uniform quality and more suitable for subsequent smelting processes.

[0019] This invention replaces the dynamic rotary kiln in the traditional production process with a static suspension calcination kiln. Compared with the traditional vertical kiln plus rotary kiln production process system, it has the advantages of simple maintenance, low operation and management costs, and long service life. Attached Figure Description

[0020] Figure 1 This is an example diagram of a process system for suspending and calcining dolomite according to the present invention;

[0021] In the diagram: 1-1, First-stage cyclone preheater; 1-2, Second-stage cyclone preheater; 1-3, Third-stage cyclone preheater; 1-4, Fourth-stage cyclone preheater; 1-5, Fifth-stage cyclone preheater; 1-6, Sixth-stage cyclone preheater; 2, calcining furnace; 3-1, First-stage cyclone cooler; 3-2, First-stage fluidized bed cooler; 3-3, Second-stage cyclone cooler; 3-4, Second-stage fluidized bed cooler; 3-5, Third-stage cyclone cooler; 1-6, Sixth-stage cyclone preheater; 4, Finished product conveying device. Detailed Implementation

[0022] The technical solutions of the present invention will now be described in detail with reference to the accompanying drawings of the embodiments.

[0023] like Figure 1 As shown, a process system for calcining dolomite in suspension includes multiple rows of multi-stage preheating devices, a calcining furnace, and a multi-stage cooling device. The multi-stage preheating device is characterized by comprising one or more sets of cyclone preheaters, with each stage connected sequentially to the next stage cyclone preheater, up to the penultimate stage. The penultimate stage cyclone preheater is connected to the inlet of the calcining furnace. The calcining furnace contains multiple sets of burners. The outlet of the calcining furnace is connected to the last stage cyclone preheater for gas-solid separation, and then connected to the multi-stage cooling device. The multi-stage cooling device includes cyclone coolers and fluidized bed coolers. Both the first and last stage cooling devices employ cyclone coolers, and fluidized bed coolers are connected between the cyclone coolers.

[0024] The top of the calcining furnace is equipped with a flue gas pipeline, which connects sequentially from the last stage cyclone preheater to the first stage cyclone preheater, and finally from the first stage cyclone preheater to the waste heat recovery device.

[0025] The multi-stage cooling device is equipped with oxygen-containing hot air pipes, which are connected sequentially. The first-stage cooling device is connected to the calcining furnace, and the last-stage cooling device is connected to an external dust collection device.

[0026] Both the final stage cooling device and the fluidized cooler are equipped with discharge pipes, and the finished product discharge pipes are connected to the finished product conveying device.

[0027] The cooling temperature of the finished material sent to the finished product conveying device is 50℃-100℃.

[0028] The calcination temperature of the calcining furnace is 860℃-920℃.

[0029] The material preheating temperature is 600℃-800℃.

[0030] Electric valves are installed between each connecting pipe.

[0031] See Figure 1 In this embodiment, the preheating device includes a first-stage cyclone preheater 1-1, a second-stage cyclone preheater 1-2, a third-stage cyclone preheater 1-3, a fourth-stage cyclone preheater 1-4, a fifth-stage cyclone preheater 1-5, and a sixth-stage cyclone preheater 1-6. In the preheating device, each of the first to sixth stage cyclone preheaters has a feed inlet and a flue gas inlet on its top side, a discharge outlet at its bottom, and a flue gas outlet at its top.

[0032] In this embodiment of the preheating device, dolomite raw material is introduced into the inlet of the first-stage cyclone preheater 1-1. The flue gas outlet of the first-stage cyclone preheater 1-1 is connected to an external waste heat recovery device, and the outlet of the first-stage cyclone preheater 1-1 is connected to the inlet of the second-stage cyclone preheater 1-2. The outlet of the second-stage cyclone preheater 1-2 is connected to the inlet of the third-stage cyclone preheater 1-3, and the flue gas outlet of the second-stage cyclone preheater 1-2 is connected to the flue gas inlet of the first-stage cyclone preheater 1-1. The outlet of the third-stage cyclone preheater 1-3 is connected to the inlet of the fourth-stage cyclone preheater 1-4, and the flue gas outlet of the third-stage cyclone preheater 1-3 is connected to the flue gas inlet of the second-stage cyclone preheater 1-2. The discharge port of the fourth-stage cyclone preheater 1-4 is connected to the inlet of the fifth-stage cyclone preheater 1-5, and the flue gas outlet of the fourth-stage cyclone preheater 1-4 is connected to the flue gas inlet of the third-stage cyclone preheater 1-3. The discharge port of the fifth-stage cyclone preheater 1-5 is connected to the calcining furnace 2, and the flue gas outlet of the fifth-stage cyclone preheater 1-5 is connected to the flue gas inlet of the fourth-stage cyclone preheater 1-4. The inlet of the sixth-stage cyclone preheater 1-6 is connected to the discharge port at the top of the calcining furnace 2, the discharge port of the sixth-stage cyclone preheater 1-6 is connected to the discharge port of the first-stage cyclone cooler 3-1, and the flue gas outlet of the sixth-stage cyclone preheater 1-6 is connected to the flue gas inlet of the fifth-stage cyclone preheater 1-5.

[0033] The calcining furnace 2 in this embodiment includes an axially vertical furnace body. The top of the furnace body has a discharge port connected to a flue gas discharge pipe and a material discharge pipe. The side of the furnace body has a feed port connected to the discharge port of the fifth-stage cyclone preheater 1-5. There are one or more feed ports. The side of the furnace body is also equipped with a fuel injection device and an ignition device.

[0034] The cooling device 3 in this embodiment includes a first-stage cyclone cooler 3-1, a first-stage fluidized bed cooler 3-2, a second-stage cyclone cooler 3-3, a second-stage fluidized bed cooler 3-4, a third-stage cyclone cooler 3-5, and a sixth-stage cyclone preheater 1-6. The outlet of the sixth-stage cyclone preheater 1-6 is connected to the inlet of the second-stage cyclone cooler 3-1; the outlet of the first-stage cyclone cooler 3-1 is connected to the inlet of the first-stage fluidized bed cooler 3-2; the flue gas outlet of the first-stage cyclone cooler 3-1 is connected to the bottom flue gas inlet of the calcining furnace 2; the bottom outlet of the first-stage fluidized bed cooler 3-2 is connected to the finished product conveying device 4; the flue gas and material outlet of the first-stage fluidized bed cooler 3-2 is connected to the flue gas and material inlet of the second-stage cyclone cooler 3-3; and the flue gas outlet of the second-stage cyclone cooler 3-3 is connected to the flue gas inlet of the first-stage cyclone cooler 3-1. The gas inlet is connected, the outlet of the second-stage cyclone cooler 3-3 is connected to the inlet of the second-stage fluidized bed cooler 3-4, the outlet and flue gas outlet of the second-stage cyclone cooler 3-3 are connected to the inlet of the third-stage cyclone cooler 3-5, the outlet and flue gas outlet of the second-stage fluidized bed cooler 3-4 are connected to the inlet of the third-stage cyclone cooler 3-5, the bottom outlet of the second-stage fluidized bed cooler 3-4 is connected to the finished product conveying device 4, the flue gas outlet of the third-stage cyclone cooler 3-5 is connected to the dust collection device, and the outlet of the third-stage cyclone cooler 3-5 is connected to the finished product conveying device 4.

[0035] After grinding and homogenization, the raw dolomite is fed into the inlet of the first-stage cyclone preheater 1-1 via a metering device, conveying device, and lifting device. The cold material in the first-stage cyclone preheater 1-1 is mixed with the hot flue gas from the second-stage cyclone preheater 1-2. After heat exchange and gas-solid separation, the flue gas generated by the first-stage cyclone preheater 1-1 is discharged from its respective top flue gas outlet into the waste heat recovery device, and the preheated raw material is discharged from its respective bottom outlet into the second-stage cyclone preheater 1-2.

[0036] In the second-stage cyclone preheater 1-2, the discharge material from the first-stage cyclone preheater is mixed with the hot flue gas from the corresponding third-stage cyclone preheater 1-3. After heat exchange and gas-solid separation, the flue gas generated by the second-stage cyclone preheater 1-2 is discharged from its respective top flue gas outlet and then enters the first-stage cyclone preheater 1-1. The preheated raw material is discharged from the bottom outlet of the second-stage cyclone preheater 1-2 to the third-stage cyclone preheater 1-3.

[0037] In the third-stage cyclone preheater 1-3, the discharge material from the second-stage cyclone preheater is mixed with the hot flue gas from the corresponding fourth-stage cyclone preheater 1-4. After heat exchange and gas-solid separation, the flue gas generated by the third-stage cyclone preheater 1-3 is discharged from the flue gas outlet at the top of its respective stage and then enters the second-stage cyclone preheater 1-2. The preheated raw material is discharged from the discharge port at the bottom of the third-stage cyclone preheater 1-3 to the fourth-stage cyclone preheater 1-4.

[0038] In the fourth-stage cyclone preheater 1-4, the discharge material from the third-stage cyclone preheater is mixed with the hot flue gas from the corresponding fifth-stage cyclone preheater 1-5. After heat exchange and gas-solid separation, the flue gas generated by the fourth-stage cyclone preheater 1-4 is discharged from the flue gas outlet at the top of its respective stage and then enters the third-stage cyclone preheater 1-3. The preheated raw material is discharged from the discharge port at the bottom of the fourth-stage cyclone preheater 1-4 to the fifth-stage cyclone preheater 1-5.

[0039] In the fifth-stage cyclone preheater 1-5, the discharge material from the fourth-stage cyclone preheater is mixed with the hot flue gas from the corresponding first-stage cyclone cooler 1-6. After heat exchange and gas-solid separation, the flue gas generated by the fifth-stage cyclone preheater 1-5 is discharged from the flue gas outlet at the top of each stage and then enters the fourth-stage cyclone preheater 1-4. The preheated raw material is discharged from the discharge port at the bottom of the fifth-stage cyclone preheater 1-5 into the calcining furnace 2 for further calcination and decomposition.

[0040] Inside the calcining furnace 2, fuel is injected into the bottom burner for combustion, maintaining the calcination temperature of the furnace at 860℃-920℃ to achieve complete decomposition of the dolomite raw material. The flue gas generated by the calcining furnace 2 carries the decomposed finished material into the sixth-stage cyclone preheaters 1-6 for further heating until the material is completely decomposed.

[0041] After the first-stage cyclone cooler 3-1 initially cools the small-diameter material discharged from the calcining furnace 2, it is discharged to the first-stage fluidized bed cooler 3-2 for further cooling. In the first-stage fluidized bed cooler 3-2, some of the cooled finished material is directly discharged to the finished material conveying device 4. Some of the high-temperature finished material continues to enter the second-stage cyclone cooler 3-3 for further cooling. In the second-stage cyclone cooler, the finished material is further cooled. Then, some of the finished material directly enters the third-stage cyclone cooler 3-5 through the top discharge port, and some enters the second-stage fluidized bed cooler 3-4 through the bottom discharge port. The second-stage fluidized bed cooler 3-4 can further cool most of the finished material to 50℃-100℃ through fluidized air cooling, and then discharges it to the finished material conveying device 4 through the bottom discharge port of the second-stage fluidized bed cooler 3-4. A small portion of the material, along with the flue gas, enters the third-stage cyclone cooler 3-5 through the top flue gas outlet of the second-stage fluidized bed cooler 3-4. After some materials are separated by cyclone in the third-stage cyclone cooler 3-5, the dust-laden flue gas enters the dust collection device, and the finished material is cooled to 50℃-100℃ and then discharged into the finished material conveying device 4.

[0042] In this embodiment, the preheating device can preheat the raw material particles to 650℃-800℃ before feeding them into the calcining furnace 2. The preheating device has high preheating efficiency, and the reaction temperature in the calcining furnace 2 is stable with a uniform temperature field distribution. The decomposition rate of dolomite can reach up to 100%, and there is no under-firing or over-firing phenomenon. The quality of the finished product is high. Compared with the traditional vertical kiln preheating decomposition and calcination system for dolomite, this utility model can significantly save energy and reduce consumption, and reduce the emission of air pollutants. It is the preferred system for a new dolomite calcination process.

[0043] The preferred embodiments of this utility model have been described in detail above with reference to the accompanying drawings. These embodiments are merely descriptions of preferred embodiments and are not intended to limit the concept and scope of this utility model. The various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. Such combinations, as long as they do not violate the spirit of this utility model, should also be considered as part of this disclosure. To avoid unnecessary repetition, this utility model will not further describe all possible combinations.

[0044] This utility model is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this utility model and without departing from the design idea of ​​this utility model, all modifications and improvements made by those skilled in the art to the technical solution of this utility model should fall within the protection scope of this utility model. The technical content for which protection is sought in this utility model has been fully recorded in the claims.

Claims

1. A process system for suspended calcination of dolomite, comprising multiple rows of multi-stage preheating devices, a calcining furnace, and a multi-stage cooling device; characterized in that, The multi-stage preheating device consists of one or more sets of cyclone preheaters. The first-stage preheating device is sequentially connected to the next-stage cyclone preheater, up to the penultimate-stage cyclone preheater. The penultimate-stage cyclone preheater is connected to the inlet of the calcining furnace. The calcining furnace is equipped with multiple sets of burners. The outlet of the calcining furnace is connected to the last-stage cyclone preheater for gas-solid separation. The last-stage cyclone preheater is then connected to the multi-stage cooling device. The multi-stage cooling device includes cyclone coolers and fluidized bed coolers. Both the first-stage and last-stage cooling devices use cyclone coolers, and fluidized bed coolers are connected between the cyclone coolers.

2. The process system for suspended calcination of dolomite according to claim 1, characterized in that, The top of the calcining furnace is equipped with a flue gas pipeline, which connects sequentially from the last stage cyclone preheater to the first stage cyclone preheater, and finally from the first stage cyclone preheater to the waste heat recovery device.

3. The process system for suspended calcination of dolomite according to claim 1, characterized in that, The multi-stage cooling device is equipped with oxygen-containing hot air pipes, which are connected sequentially. The first-stage cooling device is connected to the calcining furnace, and the last-stage cooling device is connected to an external dust collection device.

4. The process system for suspended calcination of dolomite according to claim 1, characterized in that, Both the final stage cooling device and the fluidized cooler are equipped with discharge pipes, which are connected to the finished product conveying device.

5. The process system for suspended calcination of dolomite according to claim 4, characterized in that, The cooling temperature of the finished material sent to the finished product conveying device is 50℃-100℃.

6. The process system for suspended calcination of dolomite according to claim 4, characterized in that, The calcination temperature of the calcining furnace is 860℃-920℃.

7. The process system for suspended calcination of dolomite according to claim 4, characterized in that, The material preheating temperature is 600℃-800℃.

8. The process system for suspended calcination of dolomite according to claim 4, characterized in that, Electric valves are installed between each connecting pipe.

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