Preparation system of ferrous sulfate monohydrate based on high temperature dehydration principle

Abstract

This invention discloses a ferrous sulfate monohydrate preparation system based on the principle of high-temperature dehydration, belonging to the field of titanium dioxide production technology. The system includes a raw material silo, a feeding screw conveyor, a drum head cover, a first drying drum, a second drying drum, a drum tail cover, a first combustion chamber, a second combustion chamber, a discharge pipe, and a return conveyor belt. The return conveyor belt transports a portion of the product from the drum tail cover outlet into the feeding screw conveyor. The tail of the first drying drum and the head of the second drying drum are connected by a non-rotating connecting assembly. The first combustion chamber feeds high-temperature flue gas into the first drying drum through the connecting assembly, and the second combustion chamber feeds high-temperature flue gas into the second drying drum. This invention achieves the goals of easy temperature control, high product purity, and high production efficiency, and effectively avoids the problem of raw materials adhering to the inner wall of the drying drum upon initial entry, thus affecting production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of titanium dioxide production technology, specifically relating to a system for producing ferrous sulfate monohydrate from ferrous sulfate heptahydrate, a byproduct of titanium dioxide production, and particularly to a ferrous sulfate monohydrate preparation system based on the principle of high-temperature dehydration. Background Technology

[0002] Titanium dioxide is one of the three major inorganic chemical products and is known as the "king of white pigments". Titanium dioxide has stable physical and chemical properties, excellent optical and electrical properties, and superior pigment performance, so its applications are very wide.

[0003] Ferrous sulfate monohydrate, a byproduct of titanium dioxide production via the sulfuric acid process, can be divided into two categories based on the entire production process: The first category is ferrous sulfate heptahydrate separated by freeze crystallization, which is dried to become ferrous sulfate monohydrate; the second category is ferrous sulfate monohydrate remaining in the waste acid filtrate due to the control of the iron-titanium ratio. During the waste acid concentration and reuse, the ferrous sulfate remains in the waste acid as ferrous sulfate monohydrate.

[0004] Ferrous sulfate heptahydrate, also known as ferrous sulfate heptahydrate, is an inorganic compound with the chemical formula FeSO4·7H2O and a melting point of 64℃. It is a major byproduct of titanium dioxide production using ilmenite as a raw material in the sulfuric acid process. Using acid-soluble titanium slag as a raw material reduces the amount of iron entering the titanium dioxide production process by removing most of the iron through smelting. This aims to reduce the amount of ferrous sulfate heptahydrate byproduct and alleviate market pressure from oversupply of this product. Depending on the ore source, the sulfuric acid process for titanium dioxide production using 1 ton of ilmenite produces 2.5 to 3.5 tons of ferrous sulfate heptahydrate. Since over 90% of titanium dioxide production facilities in China use ilmenite, a large amount of ferrous sulfate heptahydrate is generated. Direct market absorption is limited, leading to significant disposal and environmental problems.

[0005] Ferrous sulfate monohydrate is an inorganic compound with the chemical formula FeSO4·H2O and a melting point of 64℃. It is mainly used as a trace element in fertilizers, a water treatment agent, a concrete additive, and in the production of iron-based pigments. It has a wide range of applications. Therefore, using ferrous sulfate heptahydrate to produce ferrous sulfate monohydrate is an effective way to solve the problem of large quantities of ferrous sulfate heptahydrate being difficult to apply directly and causing environmental problems.

[0006] Traditional equipment for producing ferrous sulfate monohydrate by drying ferrous sulfate heptahydrate often uses a single drying drum as the drying component. This results in problems such as difficulty in controlling the drying temperature, low production efficiency, and low product purity. The reasons are as follows: High-temperature flue gas is introduced from the end of the drying drum and discharged from the beginning, causing the temperature at the end of the drum to be higher than that at the beginning. However, in the actual drying process, the raw material at the beginning of the drum has a high moisture content and requires a higher temperature for dehydration. The raw material at the end has already been partially dehydrated, so a slightly lower temperature is preferable. This is the opposite of the temperature difference in the drying drum of traditional equipment. If the introduced flue gas temperature is too high, all the moisture in the ferrous sulfate monohydrate will be removed, and ferrous sulfate monohydrate will not be obtained. If the introduced flue gas temperature is not high enough, not only will the production efficiency be reduced, but ferrous sulfate dihydrate and ferrous sulfate trihydrate may also be produced, making it impossible to obtain high-purity ferrous sulfate monohydrate. Meanwhile, traditional equipment also has the problem that the high moisture content of the feed material makes it easy to adhere to the first end of the drying drum wall, resulting in low production efficiency or even affecting normal production. In addition, traditional equipment also has the problem that direct storage of the discharged material can easily lead to recrystallization due to high temperature, forming ferrous sulfate dihydrate, ferrous sulfate trihydrate, etc., and inadequate dust prevention measures can cause harm to the health of workers and cause environmental pollution. Summary of the Invention

[0007] The purpose of this invention is to provide a ferrous sulfate monohydrate preparation system based on the principle of high-temperature dehydration, which is easy to control the temperature, has high product purity, and high production efficiency, in order to solve the above problems.

[0008] The present invention achieves the above objectives through the following technical solutions:

[0009] A ferrous sulfate monohydrate preparation system based on high-temperature dehydration includes a raw material silo, a feeding screw conveyor, a drum head cover, a drying drum, a drum tail cover, a combustion chamber, and a discharge pipe. The feeding screw conveyor is located below the raw material silo and is used to feed the raw material into the drying drum. The drum head cover and the drum tail cover are respectively installed at the head and tail of the drying drum. The head of the drying drum is higher than the tail and can rotate. The combustion chamber is used to supply high-temperature flue gas to the drying drum. The upper feed end of the discharge pipe is connected to the lower discharge end of the drum tail cover. The ferrous sulfate monohydrate preparation system based on high-temperature dehydration also includes a return conveyor belt. A return pipe is installed at the lower end of the drum tail cover or on the discharge pipe. A return valve is installed on the return pipe. The feed end of the return conveyor belt... Located below the return pipe, the discharge end of the return conveyor belt is close to the head of the drying drum and is used to transport part of the product from the drum tail cover outlet into the feed screw conveyor. The drying drum is composed of a first drying drum and a second drying drum connected together. The head of the first drying drum is the head of the drying drum, and the tail of the second drying drum is the tail of the drying drum. The tail of the first drying drum and the head of the second drying drum are connected by a connecting component, and the connecting component cannot rotate. The combustion chamber includes a first combustion chamber and a second combustion chamber. The first combustion chamber sends high-temperature flue gas into the first drying drum through the connecting component, and the second combustion chamber is close to the tail of the second drying drum and sends high-temperature flue gas into the second drying drum.

[0010] Preferably, to facilitate the uniform delivery of high-temperature flue gas from the first combustion chamber into the drying drum, the connecting assembly includes an annular outer connecting cylinder and an annular inner connecting cylinder. The outer connecting cylinder is fitted over the inner connecting cylinder. The inner circumferential wall of the outer connecting cylinder has a concave ring, and the outer circumferential wall of the outer connecting cylinder has an interface communicating with the concave ring, which is connected to the high-temperature flue gas pipe of the first combustion chamber. The inner connecting cylinder has multiple radially penetrating air inlets along the circumferential direction. The outer ends of all the air inlets are located within the concave ring, and the inner ends of the air inlets communicate with the first drying drum and the second drying drum. The tail of the first drying drum and the head of the second drying drum are located outside the axial ends of the inner connecting cylinder and are respectively connected to each other.

[0011] Preferably, in order to allow most of the high-temperature flue gas in the first combustion chamber to enter the first drying drum more quickly for high-temperature dehydration of the feed with high humidity, and at the same time to use part of the high-temperature flue gas in the first combustion chamber to push the raw material passing through the inner connecting cylinder downward to avoid the accumulation of the raw material, the multiple air inlet holes in the upper middle part of the inner connecting cylinder are all upward air inlet holes, and the section of the upward air inlet hole near the inner end is bent towards the first drying drum. The multiple air inlet holes in the lower part of the inner connecting cylinder are all downward air inlet holes, and the section of the downward air inlet hole near the inner end is bent towards the second drying drum.

[0012] Preferably, for ease of processing and assembly, and to ensure a good sealing effect between the inner connecting cylinder and the two drying drums, the two axial ends of the inner connecting cylinder extend outwards near their outer peripheral edges to form limiting rings. The inner walls of the two limiting rings are respectively in contact with the outer wall of the tail of the first drying drum and the outer wall of the head of the second drying drum. The circumferential inner wall surfaces of the inner connecting cylinder, the first drying drum, and the second drying drum are flush with each other. Circular annular bosses are respectively provided on the outer circumferential outer wall of the first drying drum near its tail and on the outer circumferential outer wall of the second drying drum near its head. The outer ends of the two limiting rings are close to the corresponding ends of the two annular bosses and a first sealing ring is installed in the gap. The axial ends of the inner circumferential inner walls of the outer connecting cylinder are respectively provided with "L"-shaped annular grooves, and the corresponding ends of the two annular bosses are respectively placed in the two annular grooves.

[0013] Preferably, in order to achieve a better sealing effect, a second sealing ring is installed between the corresponding end of the annular boss and the groove wall of the corresponding annular groove of the outer connecting cylinder.

[0014] Preferably, in order to achieve a better sealing effect, the outer walls of both ends of the outer connecting cylinder are respectively connected to one end of two sets of elastic sealing sheets, and the other ends of the two sets of elastic sealing sheets are respectively in contact with the outer walls of the two annular bosses.

[0015] Preferably, in order to achieve more precise temperature control of the first drying drum and the second drying drum, a first temperature sensor is provided on the wall of the first drying drum, and a second temperature sensor is provided on the wall of the second drying drum. The signal output terminals of the first temperature sensor and the second temperature sensor are respectively connected to the signal input terminal of the controller or to the signal input terminal of the temperature display.

[0016] Preferably, in order to facilitate feeding and achieve better mixing between raw materials and return materials, a discharge screw conveyor is installed below the lower outlet of the raw material silo, and a feeding conveyor belt is installed below the outlet of the discharge screw conveyor. The feeding end of the feeding screw conveyor is located below the outlet of the feeding conveyor belt, and the discharge end of the return conveyor belt is located above the feeding conveyor belt.

[0017] Preferably, in order to cool the finished product ferrous sulfate monohydrate in a timely manner to prevent crystallization, the lower discharge end of the discharge pipe is connected to the feed end of the slag cooler, the discharge end of the slag cooler is located above the feed end of the discharge conveyor belt, the lower feed end of the bucket elevator is located below the discharge end of the discharge conveyor belt, and the upper discharge end of the bucket elevator is connected to the feed port of the finished product silo through a conveying pipe.

[0018] Preferably, to achieve better environmental protection, a dust cover is installed above the discharge conveyor belt, and a first bag filter is installed above the dust cover. The dust cover and the discharge pipe are respectively connected to the inlet of the first bag filter through pipes. The outlet of the first bag filter is connected to the discharge end of the discharge conveyor belt through a pipe. A second bag filter is installed above the finished product bin. The roller head cover is connected to the air inlet of the exhaust gas processor through an exhaust pipe.

[0019] The beneficial effects of this invention are as follows:

[0020] This invention improves the traditional single drying drum into two drying drums connected by a non-rotating connecting component. High-temperature flue gas is introduced into the two drying drums through two combustion chambers, making the temperature in the first drying drum near the feed end higher than the temperature in the second drying drum near the discharge end. This meets the practical application requirements of faster dehydration at the feed end and a slightly lower temperature required at the discharge end. It also facilitates segmented temperature control to achieve segmented dehydration of raw materials, resulting in higher purity ferrous sulfate monohydrate. Ultimately, it achieves the goals of easy temperature control, high product purity, and high production efficiency. Furthermore, by feeding a portion of the high-temperature finished product into the feed end to mix with the raw materials with higher moisture content, the moisture content of the raw materials is quickly reduced, effectively avoiding the problem of raw materials adhering to the inner wall of the drying drum and affecting production efficiency when they first enter the drying drum. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the main structure of the ferrous sulfate monohydrate preparation system based on the high-temperature dehydration principle described in this invention;

[0022] Figure 2 This is a front cross-sectional view of the connecting components of the ferrous sulfate monohydrate preparation system based on the high-temperature dehydration principle described in this invention. The scale of the figure is larger than [missing information]. Figure 1 And the perspective is the same;

[0023] Figure 3 This is a left-side view of the inner connecting cylinder of the ferrous sulfate monohydrate preparation system based on the high-temperature dehydration principle described in this invention. The proportions in the figure are similar to those in the original. Figure 2 same. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings:

[0025] like Figures 1-3 As shown, the ferrous sulfate monohydrate preparation system based on the high-temperature dehydration principle of the present invention includes a raw material silo 1, a feeding screw conveyor 4, a drum head cover 5, a drying drum (refer to the first drying drum 11 and the second drying drum 21 below), a drum tail cover 23, a combustion chamber (refer to the first combustion chamber 16 and the second combustion chamber 24 below), a discharge pipe 26, and a return conveyor belt 9. The feeding screw conveyor 4 is located below the raw material silo 1 and is used to feed the raw material into the drying drum. The drum head cover 5 and the drum tail cover 23 are respectively installed at the head and tail of the drying drum. The head of the drying drum is higher than the tail and can rotate. The inclination of the drying drum is determined as needed, generally at an angle of 3-5° with the horizontal direction. The combustion chamber is used to feed high-temperature flue gas into the drying drum. The upper feed end of the discharge pipe 26 is connected to the lower discharge end of the drum tail cover 23. A return conveyor belt 9 is installed at the lower end of the drum tail cover 23 (or at a certain position on the discharge pipe 26). The material pipe (not marked in the figure) is equipped with a return valve 25. The feed end of the return conveyor belt 9 is located below the return pipe. The discharge end of the return conveyor belt 9 is close to the head of the drying drum and is used to transport part of the product from the outlet of the drum tail cover 23 into the feed screw conveyor 4. The drying drum is formed by connecting a first drying drum 11 and a second drying drum 21. The head of the first drying drum 11 is the head of the drying drum, and the tail of the second drying drum 21 is the tail of the drying drum. The tail of the first drying drum 11 and the head of the second drying drum 21 are connected by a connecting component 17, and the connecting component 17 cannot rotate. The combustion chamber includes a first combustion chamber 16 and a second combustion chamber 24. The first combustion chamber 16 feeds high-temperature flue gas into the first drying drum 11 through the connecting component 17. The second combustion chamber 24 is close to the tail of the second drying drum 21 and feeds high-temperature flue gas into the second drying drum 21. An air hammer is also installed on the side wall of raw material silo 1 to periodically knock on the outer wall of raw material silo 1 to prevent material bridging caused by ferrous sulfate heptahydrate sticking to the wall, which would prevent normal material discharge.

[0026] like Figures 1-3 As shown, the present invention also discloses the following more optimized specific structures:

[0027] To facilitate the uniform delivery of the high-temperature flue gas from the first combustion chamber 16 into the drying drum, the connecting assembly 17 includes an annular outer connecting cylinder 40 and an annular inner connecting cylinder 43. The outer connecting cylinder 40 is fitted over the inner connecting cylinder 43. The outer connecting cylinder 40 is mounted on the ground or other equipment via a mounting bracket (not shown in the figure). The inner circumference of the outer connecting cylinder 40 is provided with a recessed ring 41, and the outer circumference of the outer connecting cylinder 40 is provided with an interface (not marked in the figure) communicating with the recessed ring 41. This interface is connected to the first combustion chamber 16. The high-temperature flue gas pipe 15 of the combustion chamber 16 is connected to the inner connecting cylinder 43. Multiple radially penetrating air inlet holes are provided in the inner wall of the inner connecting cylinder 43 along the circumferential direction (refer to the upper air inlet hole 42 and the lower air inlet hole 46 below). The outer ends of all the air inlet holes are located inside the concave ring 41. The inner ends of the air inlet holes are connected to the first drying drum 11 and the second drying drum 21. The tail of the first drying drum 11 and the head of the second drying drum 21 are located outside the two axial ends of the inner connecting cylinder 43 and are respectively connected to each other.

[0028] To allow most of the high-temperature flue gas from the first combustion chamber 16 to enter the first drying drum 11 more quickly for high-temperature dehydration of the feed material with high humidity, and to utilize some of the high-temperature flue gas from the first combustion chamber 16 to push the raw material passing through the inner connecting cylinder 43 downwards to avoid material accumulation, multiple air inlet holes in the upper middle part of the inner connecting cylinder 43 are upward air inlet holes 42. A section of the upward air inlet hole 42 near its inner end is bent towards the first drying drum 11 (the bending angle depends on actual needs; for example, after bending, the angle between its centerline and the axis of the inner connecting cylinder 43 is 80°). This allows... This allows the high-temperature flue gas to flow upwards more quickly, towards the head of the first drying drum 11, resulting in a higher temperature and faster temperature rise inside the first drying drum 11. The multiple air inlets in the lower wall of the inner connecting cylinder 43 are all downward air inlets 46. A section of the downward air inlet 46 near its inner end bends towards the second drying drum 21 (the bending angle depends on actual needs; for example, after bending, the angle between its centerline and the axis of the inner connecting cylinder 43 is 80°). This allows the high-temperature flue gas to flow downwards more quickly, towards the tail of the second drying drum 21, thus propelling the raw material into the second drying drum 21 rapidly.

[0029] To facilitate processing and assembly, and to ensure a good sealing effect between the inner connecting cylinder 43 and the two drying drums, the two axial ends of the inner connecting cylinder 43 extend outwards near the outer peripheral edge to form limiting rings 44. The inner walls of the two limiting rings 44 are respectively in contact with the outer wall of the tail of the first drying drum 11 and the outer wall of the head of the second drying drum 21. The inner circumferential surfaces of the inner connecting cylinder 43, the first drying drum 11, and the second drying drum 21 are flush with each other. The outer circumferential surfaces of the first drying drum 11 near the tail and the second drying drum 21 near the head are respectively provided with annular protrusions 37. The outer ends of the two limiting rings 44 are close to the corresponding ends of the two annular protrusions 37 and a first sealing ring 45 is installed in the gap. The inner circumferential surfaces of the two axial ends of the outer connecting cylinder 40 are respectively provided with "L"-shaped annular grooves (not marked in the figure), and the corresponding ends of the two annular protrusions 37 are respectively placed in the two annular grooves.

[0030] To achieve a better sealing effect, a second sealing ring 39 is installed between the corresponding end of the annular boss 37 and the groove wall of the corresponding annular groove of the outer connecting cylinder 40.

[0031] To achieve a better sealing effect, the outer walls of the two ends of the outer connecting cylinder 40 are respectively connected to one end of the two sets of elastic sealing plates 38, and the other ends of the two sets of elastic sealing plates 38 are respectively in contact with the outer walls of the two annular bosses 37.

[0032] To achieve more precise temperature control of the first drying drum 11 and the second drying drum 21, a first temperature sensor 10 is installed on the drum wall of the first drying drum 11 (the installation location is determined according to actual needs, whether it is installed on the inner or outer wall, and whether it is installed in the middle, head, or tail section). A second temperature sensor 19 is installed on the drum wall of the second drying drum 21 (the installation location is determined according to actual needs, whether it is installed on the inner or outer wall, and whether it is installed in the middle, head, or tail section). The signal output terminals of the first temperature sensor 10 and the second temperature sensor 19 are respectively connected to the signal input terminal of the controller (not shown in the figure) or to the signal input terminal of the temperature display (not shown in the figure).

[0033] To facilitate feeding and achieve better mixing between raw materials and return materials, a discharge screw conveyor 2 is installed below the lower outlet of the raw material silo 1. A feeding conveyor belt 3 is installed below the outlet of the discharge screw conveyor 2. The feeding end of the feeding screw conveyor 4 is located below the outlet of the feeding conveyor belt 3, and the discharge end of the return conveyor belt 9 is located above the feeding conveyor belt 3.

[0034] In order to cool the finished product ferrous sulfate monohydrate in time to prevent crystallization, the lower discharge end of the discharge pipe 26 is connected to the feed end of the slag cooler 28. The discharge end of the slag cooler 28 is located above the feed end of the discharge conveyor belt 29. The lower feed end of the bucket elevator 32 is located below the discharge end of the discharge conveyor belt 29. The upper discharge end of the bucket elevator 32 is connected to the feed port of the finished product bin 33 through a conveying pipe.

[0035] To achieve better environmental protection, a dust cover 30 is installed above the discharge conveyor belt 29, and a first bag filter 31 is installed above the dust cover 30. The dust cover 30 and the discharge pipe 26 are respectively connected to the inlet of the first bag filter 31 through pipes. The outlet of the first bag filter 31 is connected to the discharge end of the discharge conveyor belt 29 through a pipe. A second bag filter 34 is installed on the upper part of the finished product bin 33. The roller head cover 5 is connected to the air inlet of the exhaust gas processor 7 through an exhaust pipe.

[0036] Figure 1 The diagram also shows a material receiver 6 located below the drum head cover 5; a first star-shaped unloader 8 installed at the lower part of the exhaust gas processor 7; a first driven gear 12 mounted on the outer wall of the first drying drum 11; the shaft of the first drive motor 14 connected to the first driving gear (not marked in the figure); the first driving gear meshing with the first driven gear 12 to drive the rotation of the first drying drum 11; two first drag wheels 13 positioned near the head and tail of the first drying drum 11 respectively; the first drag wheels 13 mounted on the ground or other equipment via mounting brackets (not shown in the figure) to support the first drying drum 11 and enable its free rotation; and a second driven gear 20 mounted on the second drying drum. On the outer wall of 21, the shaft of the second drive motor 22 is connected to the second driving gear (not marked in the figure). The second driving gear meshes with the second driven gear 20 to drive the rotation of the second drying drum 21. The second drying drum 21 is placed on two second drag wheels 18 near the head and tail, respectively. The second drag wheels 18 are mounted on the ground or other equipment by mounting brackets (not shown in the figure) to support the second drying drum 21 and enable the second drying drum 21 to rotate freely. The lower discharge end of the discharge pipe 26 is also provided with an emergency discharge port 27. The lower part of the finished product bin 33 is provided with a second star-shaped unloader 35, and the packaging machine 36 is located below the second star-shaped unloader 35. These structures are all conventional and adaptable structures.

[0037] like Figure 1 - Figure 3As shown, in application, the raw material ferrous sulfate heptahydrate enters the discharge screw conveyor 2 through the lower outlet of the raw material silo 1. The discharge screw conveyor 2 then delivers the raw material to the feed conveyor belt 3 in a timed and quantitative manner. Simultaneously, the high-temperature finished ferrous sulfate monohydrate from the return conveyor belt 9 is sent to the feed conveyor belt 3. After simple mixing with the ferrous sulfate heptahydrate, the mixture is sent to the feed screw conveyor 4. The ferrous sulfate heptahydrate and ferrous sulfate monohydrate are mixed again in the feed screw conveyor 4, and their temperatures gradually converge. During this process, the free water in the ferrous sulfate heptahydrate decreases due to evaporation, reducing its viscosity. The ferrous sulfate monohydrate crystallizes into ferrous sulfate heptahydrate or ferrous sulfate hexahydrate, etc. The mixed raw materials then enter the head of the first drying drum 11. The high-temperature flue gas in the first drying drum 11 dehydrates the raw materials at high temperature. The free water in the ferrous sulfate heptahydrate is evaporated at high temperature, and some of the crystal water in the ferrous sulfate heptahydrate also evaporates as free water. This process continues as the first drying drum 11 rotates. During the process, the material gradually reaches the tail end of the first drying drum 11. During this process, ferrous sulfate heptahydrate (or ferrous sulfate hexahydrate) dehydrates into ferrous sulfate tetrahydrate or ferrous sulfate trihydrate, and then enters the head of the second drying drum 21 through the inner connecting cylinder 43. During this process, some of the high-temperature flue gas from the first combustion chamber 16 blows the raw material located in the lower middle part of the inner connecting cylinder 43, allowing it to descend smoothly and preventing accumulation. The ferrous sulfate tetrahydrate or ferrous sulfate trihydrate is then processed by the second combustion chamber 16 within the second drying drum 21. The high-temperature flue gas in the combustion chamber 24 continues to be heated and dehydrated. When it reaches the tail of the second drying drum 21, it is dehydrated into ferrous sulfate monohydrate. Then, it passes through the drum tail cover 23 and the discharge pipe 26 and enters the slag cooler 28 for rapid cooling. After the slag cooler 28 cools the ferrous sulfate monohydrate from 58-63℃ to 20-25℃, the ferrous sulfate monohydrate is sent to the lower feed end of the bucket elevator 32 via the discharge conveyor belt 29. After being lifted by the bucket elevator 32, it is sent to the finished product warehouse 33 for storage or packaged by the packaging machine 36.

[0038] During operation, the temperatures inside the first drying drum 11 and the second drying drum 21 are detected in real time by the first temperature sensor 10 and the second temperature sensor 19, respectively. This is used as the basis for controlling the duration of high-temperature flue gas from the first combustion chamber 16 and the second combustion chamber 24 being sent into the first drying drum 11 and the second drying drum 21. The temperatures inside the first drying drum 11 and the second drying drum 21 are adjusted in real time, thereby achieving a more precise temperature control function, resulting in higher purity and higher production efficiency of the ferrous sulfate monohydrate product.

[0039] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the technical solutions of the present invention. Any technical solution that can be implemented based on the above embodiments without creative effort should be considered to fall within the scope of protection of the patent of the present invention.

Claims

1. A ferrous sulfate monohydrate preparation system based on high-temperature dehydration principle, comprising a raw material bin, a feeding screw conveyor, a drum head cover, a drying drum, a drum tail cover, a combustion chamber and a discharge pipe, the feeding screw conveyor is located below the raw material bin and is used to send raw materials into the drying drum, the drum head cover and the drum tail cover are respectively installed at the head and tail of the drying drum, the head of the drying drum is higher than the tail and can rotate, the combustion chamber is used to send high-temperature flue gas into the drying drum, and the upper feeding end of the discharge pipe is connected with the lower discharging end of the drum tail cover, characterized in that: The ferrous sulfate monohydrate preparation system based on the high-temperature dehydration principle also includes a return conveyor belt. A return pipe is installed at the lower end of the drum tail cover or on the discharge pipe. A return valve is installed on the return pipe. The inlet end of the return conveyor belt is located below the return pipe. The outlet end of the return conveyor belt is close to the head of the drying drum and is used to transport part of the product from the drum tail cover outlet into the feed screw conveyor. The drying drum is composed of a first drying drum and a second drying drum connected together. The head of the first drying drum is the head of the drying drum, and the tail of the second drying drum is the tail of the drying drum. The tail of the first drying drum and the head of the second drying drum are connected by a connecting assembly, and the connecting assembly cannot rotate. The combustion chamber includes a first combustion chamber and a second combustion chamber. The first combustion chamber sends high-temperature flue gas into the first drying drum through the connecting assembly. The second combustion chamber is close to the tail of the second drying drum and sends high-temperature flue gas into the second drying drum. The connecting assembly includes... The outer connecting cylinder and the inner connecting cylinder are circularly annular. The outer connecting cylinder is fitted over the inner connecting cylinder. The inner circumference of the outer connecting cylinder has a concave ring. The outer circumference of the outer connecting cylinder has an interface communicating with the concave ring and connected to the high-temperature flue gas pipe of the first combustion chamber. The inner connecting cylinder has multiple radially penetrating air inlets along the circumferential direction inside its cylinder wall. The outer ends of all the air inlets are located inside the concave ring. The inner ends of the air inlets are connected to the first drying roller and the second drying roller. The inner connecting cylinders are connected, with the tail end of the first drying drum and the head end of the second drying drum located at the axial ends of the inner connecting cylinder and respectively connected to each other; the multiple air inlet holes in the upper middle part of the inner connecting cylinder are all upward air inlet holes, and a section of the upward air inlet hole near the inner end bends towards the first drying drum; the multiple air inlet holes in the lower part of the inner connecting cylinder are all downward air inlet holes, and a section of the downward air inlet hole near the inner end bends towards the second drying drum.

2. The ferrous sulfate monohydrate preparation system based on the high-temperature dehydration principle according to claim 1, characterized in that: The inner connecting cylinder has two axial ends extending outward from near its outer periphery to form limiting rings. The inner walls of the two limiting rings are respectively in contact with the outer wall of the tail of the first drying drum and the outer wall of the head of the second drying drum. The inner circumferential surfaces of the inner connecting cylinder, the first drying drum, and the second drying drum are flush with each other. The outer circumferential surfaces of the first drying drum and the second drying drum are respectively provided with annular protrusions near the tail and near the head. The outer ends of the two limiting rings are close to the corresponding ends of the two annular protrusions and a first sealing ring is installed in the gap. The inner circumferential surfaces of the two outer connecting cylinder have "L"-shaped annular grooves, and the corresponding ends of the two annular protrusions are respectively placed in the two annular grooves.

3. The ferrous sulfate monohydrate preparation system based on the high-temperature dehydration principle according to claim 2, characterized in that: A second sealing ring is installed between the corresponding end of the annular boss and the groove wall of the corresponding annular groove of the outer connecting cylinder.

4. The ferrous sulfate monohydrate preparation system based on the high-temperature dehydration principle according to claim 3, characterized in that: The outer walls of the two axial ends of the outer connecting cylinder are respectively connected to one end of two sets of elastic sealing sheets, and the other ends of the two sets of elastic sealing sheets are respectively in contact with the outer walls of the two annular bosses.

5. The ferrous sulfate monohydrate preparation system based on the high-temperature dehydration principle according to any one of claims 1-4, characterized in that: The first drying drum is provided with a first temperature sensor on its drum wall, and the second drying drum is provided with a second temperature sensor on its drum wall. The signal output terminals of the first temperature sensor and the second temperature sensor are respectively connected to the signal input terminal of the controller or to the signal input terminal of the temperature display.

6. The ferrous sulfate monohydrate preparation system based on the high-temperature dehydration principle according to any one of claims 1-4, characterized in that: A discharge screw conveyor is installed below the lower outlet of the raw material silo, and a feed conveyor belt is installed below the outlet of the discharge screw conveyor. The feed end of the feed screw conveyor is located below the outlet of the feed conveyor belt, and the discharge end of the return conveyor belt is located above the feed conveyor belt.

7. The ferrous sulfate monohydrate preparation system based on the high-temperature dehydration principle according to any one of claims 1-4, characterized in that: The lower discharge end of the discharge pipe is connected to the feed end of the slag cooler. The discharge end of the slag cooler is located above the feed end of the discharge conveyor belt. The lower feed end of the bucket elevator is located below the discharge end of the discharge conveyor belt. The upper discharge end of the bucket elevator is connected to the feed inlet of the finished product silo through a conveying pipe.

8. The ferrous sulfate monohydrate preparation system based on the high-temperature dehydration principle according to claim 7, characterized in that: A dust cover is installed above the discharge conveyor belt, and a first bag filter is installed above the dust cover. The dust cover and the discharge pipe are respectively connected to the inlet of the first bag filter through pipes. The outlet of the first bag filter is connected to the discharge end of the discharge conveyor belt through a pipe. A second bag filter is installed above the finished product bin. The roller head cover is connected to the air inlet of the exhaust gas processor through an exhaust pipe.

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