Ceramsite production process

Abstract

The present invention relates to a ceramsite production process, and belongs to the technical field of ceramsite preparation, the ceramsite production process comprises the following steps: S100, tailings and muck are crushed and ground to obtain tailings powder with a particle size of not more than 200 meshes, muck powder, the tailings powder, the muck powder and sludge are mixed to obtain a mixture, the water content of the mixture is not higher than 20%, and the calcium content of the mixture is not higher than 8%; s200, the mixture is sent into an aging room to be aged, the aged mixture is sent into a granulator to be granulated, the granulated raw material balls are sent into a dryer to be dried, and the dried material balls are sent into a cascade type rotary kiln to be roasted; and S300, the pellets obtained after high-temperature roasting and melting fall into a cooling machine to be cooled, the cooled ceramsite is screened out of different specifications according to market requirements, packaged and then fed into a finished product storage area to be stored, and the technical problem that tailings and sludge cannot be perfectly treated in the prior art can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramsite preparation, and in particular relates to a ceramsite production process. Background Art

[0002] Expanded clay is widely used as aggregate in the construction materials industry because of its advantages such as reasonable particle size distribution, low bulk density, low thermal conductivity, low water absorption, high refractoriness, good thermal insulation effect, and acid corrosion resistance.

[0003] Sludge refers to solid, semi-solid and liquid wastes produced during sewage treatment. It is a complex mixture. The new environmental protection policy requires that sludge should be stabilized, harmless and resource-based. As a by-product of sewage treatment, the amount of sludge to be treated has increased dramatically with the construction of sewage treatment plants. How to safely, effectively and low-costly complete the treatment of sludge to avoid secondary pollution to the environment has become an important research topic. The existing sludge treatment methods mainly include sanitary landfill, composting and incineration: sanitary landfill occupies a lot of land, has great safety hazards, and has a greater risk of secondary environmental pollution; composting treatment requires reducing the moisture content of sludge. Ways to reduce the moisture content include sludge drying and adding straw, sawdust and other materials. These measures reduce the efficiency of sludge treatment and increase the cost of sludge treatment; incineration will produce dust and toxic substances (such as dioxins), with high investment intensity and high technical requirements.

[0004] Tailings are solid wastes discharged from metal or non-metal mines after ore selection, such as tailings or other industrial waste. Since they contain less metal, most of them are built on the mountain to intercept the valley mouth or enclose the land to form tailings dams. Once the tailings dam collapses, it will not only cause economic losses to the country, but also endanger the lives and property of the workers and residents in the downstream areas. Due to the low recycling value of tailings, people are not very enthusiastic about the restoration and management of the mine mountain environment.

[0005] Tailings and sludge are two types of waste with relatively large output, which cause serious environmental pollution. There is currently no very complete disposal method for these two types of waste. Summary of the invention

[0006] In view of the various deficiencies of the existing technology, a ceramsite production process is now proposed to solve the technical problem that the existing technology cannot perfectly treat tailings and sludge.

[0007] To achieve the above object, the present invention provides the following technical solutions: A ceramsite production process comprises the following steps: S100, crushing and grinding the tailings and slag to obtain tailings powder and slag powder with a particle size of no more than 200 meshes, mixing the tailings powder and slag powder with the sludge to obtain a mixture, wherein the moisture content of the mixture is no more than 20%, and the calcium content of the mixture is no more than 8%; S200, the mixture is sent to an aging room for aging, the aged mixture is sent to a granulator for granulation, the granulated raw material balls are sent to a dryer for drying, and the dried material balls are sent to a waterfall rotary kiln for roasting; S300, the molten material balls after high-temperature roasting fall into the cooler for cooling. The cooled expanded clay is screened into different specifications according to market demand and packed and sent to the finished product storage area for storage.

[0008] The technical solution is further configured as follows: in S100, the sludge is red mud, river silt and / or municipal sludge, and its water content is not higher than 65%; the tailings are fly ash, coal gangue, gold tailings, iron tailings, graphite tailings and / or molybdenum tailings, and its water content is not higher than 3%; the slag is gasified slag, bentonite and / or engineering slag, and the sieve residue of the tailings powder and the slag powder does not exceed 15%.

[0009] The technical solution is further configured that the sludge needs to be transported to the sludge storage workshop by the conveying equipment for standby, and the whole process is sealed and slightly negative pressure transported. The sludge in the sludge storage workshop is dispersed by the disperser and sent to the batching hopper, and the batching hopper measures the discharge; The tailings powder is pumped to the powder silo for storage and is transported in a sealed manner throughout the entire process. The tailings powder in the powder silo is sent to the metering scale for controlled metering via a closed screw conveyor. The technical solution is further configured as follows: in S200, the mixture is sent to an aging room after being stirred, and the aging time is 48-72 hours.

[0010] The technical solution is further configured as follows: in S200, the raw material balls after granulation are firstly sent to a shaping machine for shaping, and the moisture content of the raw material balls after shaping is not higher than 20%, and the raw material balls after shaping are then sent to a drying machine for drying.

[0011] The technical solution is further configured as follows: the drying temperature of the dryer is 150°C-200°C, the moisture content of the dried pellets is not higher than 2%, and the exhaust gas discharged from the dryer meets the emission standards after dust removal, wet desulfurization and wet electrostatic dust removal.

[0012] The technical solution is further configured as follows: the roasting temperature of the waterfall rotary kiln is 1100-1500°C, the exhaust gas temperature of the waterfall rotary kiln is 800°C-850°C, the exhaust gas from the kiln is treated with SNCR denitrification and then dust removed before being sent to the heat exchange device, and the clean hot air after heat exchange is sent to the dryer.

[0013] The technical solution is further configured such that the clean cold air in the heat exchange device completes heat exchange with the kiln exhaust gas within 2 seconds to form clean hot air after heat exchange, and the temperature of the clean hot air after heat exchange is 280°C-320°C.

[0014] The technical solution is further configured such that the temperature of the exhaust gas out of the kiln after heat exchange is 100°C-150°C, and the exhaust gas is discharged after dust removal and wet desulfurization treatment.

[0015] The technical solution is further configured as follows: in S300, the clean cold air is heat exchanged by the cooler and dust removed to form clean hot air after heat exchange by the cooler, and the clean hot air after heat exchange by the cooler is transported to the dryer, and the temperature of the clean hot air after heat exchange by the cooler is 280℃-320℃.

[0016] The beneficial effects of the present invention are: 1. Using sludge and tailings as raw materials for expanded clay production has wide sources and low prices, realizing green, energy-saving, safe and efficient resource processing of sludge and tailings.

[0017] 2. The mixture is sent to the aging room for aging to ensure that the moisture in the mixture has enough time to enter the interior from the surface and be evenly distributed; the mixture is dispersed and plasticized, and the organic matter forms organic colloid substances, which further increases the plasticity of the mixture, improves the molding performance of the mixture and the performance of the finished product, ensures the stability of the material, and is conducive to the subsequent process of ball drying. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a flow chart of the ceramsite production process in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings of the present invention. Based on the embodiments in this application, other similar embodiments obtained by ordinary technicians in this field without making creative work should all fall within the scope of protection of this application. In addition, the directional words mentioned in the following embodiments, such as "up", "down", "left", "right", etc., are only reference to the directions of the accompanying drawings. Therefore, the directional words used are used to illustrate rather than limit the invention.

[0020] According to an embodiment of the present invention, a ceramsite production process is provided. Figure 1 , including the following steps: S100, crushing and grinding the tailings and slag to obtain tailings powder and slag powder with a particle size of no more than 200 meshes, mixing the tailings powder and slag powder with the sludge to obtain a mixture, wherein the moisture content of the mixture is no more than 20%, and the calcium content of the mixture is no more than 8%; S200, the mixture is sent to an aging room for aging, the aged mixture is sent to a granulator for granulation, the granulated raw material balls are sent to a dryer for drying, and the dried material balls are sent to a waterfall rotary kiln for roasting; S300, the molten material balls after high-temperature roasting fall into the cooler for cooling. The cooled expanded clay is screened into different specifications according to market demand and packed and sent to the finished product storage area for storage.

[0021] It should be noted that using sludge and tailings as raw materials for expanded clay production is widely available and inexpensive, thus achieving green, energy-saving, safe and efficient resource processing of sludge and tailings.

[0022] In the ceramsite production process of this embodiment, please refer to Figure 1 In S100, the sludge is red mud, river silt and / or municipal sludge, and its moisture content is not higher than 65%; the tailings are fly ash, coal gangue, gold tailings, iron tailings, graphite tailings and / or molybdenum tailings, and its moisture content is not higher than 3%; the slag is gasified slag, bentonite and / or engineering slag, and the sieve residue of the tailings powder and the slag powder does not exceed 15%.

[0023] Preferably, the sludge is municipal sludge, which has a moisture content of 60% and does not require dehydration treatment.

[0024] In the ceramsite production process of this embodiment, please refer to Figure 1 The sludge needs to be transported to the sludge storage workshop through the conveying equipment for standby use. The whole process is sealed and slightly negative pressure conveyed. The sludge in the sludge storage workshop is dispersed by the disperser and sent to the batching hopper, which measures the discharge. The tailings powder is pumped to the powder silo for storage and is transported in a sealed manner throughout the entire process. The tailings powder in the powder silo is sent to the metering scale for controlled metering via a closed screw conveyor. It should be noted that the sludge, tailings powder and slag powder are fed into the mixer for mixing, and the components in the materials are fully mixed through high-speed stirring to ensure the homogeneity of the mixture. Preferably, the mixer is a vertical turbulent mixer.

[0025] In the ceramsite production process of this embodiment, please refer to Figure 1 In S200, the mixture is stirred and then sent to an aging room for 48-72 hours.

[0026] It should be noted that after being stirred by the mixer, the mixture is sent to the aging room for aging. In order to ensure that the moisture in the mixture has enough time to enter the interior from the surface and be evenly distributed, the inventor optimizes the aging time to 48-72 hours, ensures the mixture is dispersed and plasticized, and the organic matter forms organic colloidal substances, which further increases the plasticity of the raw materials, improves the molding properties of the mixture and the performance of the finished product, ensures the stability of the mixture, and is beneficial to the subsequent process of ball drying.

[0027] In the ceramsite production process of this embodiment, please refer to Figure 1 In S200, the raw material balls after granulation are firstly sent to the shaping machine for shaping. The moisture content of the shaped raw material balls is not higher than 20%. The shaped raw material balls are then sent to the dryer for drying.

[0028] It should be noted that the aged mixture is sent to a buffer hopper for temporary storage, and then sent to an extrusion granulator for granulation via a metering and speed regulating device (differentiated granulation equipment is determined depending on product market requirements). Preferably, the metering and speed regulating device is the metering and speed regulating belt; the raw material balls after granulation enter a shaping machine for shaping; and the shaped raw material balls enter a dryer for drying.

[0029] In the ceramsite production process of this embodiment, please refer to Figure 1 The drying temperature of the dryer is 150°C-200°C, the moisture content of the dried pellets is not higher than 2%, and the exhaust gas discharged from the dryer meets the emission standards after dust removal, wet desulfurization and wet electrostatic dust removal.

[0030] In the ceramsite production process of this embodiment, please refer to Figure 1 The calcination temperature of the waterfall rotary kiln is 1100-1500°C, the exhaust gas temperature of the waterfall rotary kiln is 800°C-850°C, the exhaust gas is treated with SNCR denitrification and then dust removal before being sent to the heat exchange device, and the clean hot air after heat exchange is sent to the dryer.

[0031] In the ceramsite production process of this embodiment, please refer to Figure 1 The clean cold air in the heat exchange device completes heat exchange with the kiln exhaust gas within 2 seconds to form clean hot air after heat exchange, and the temperature of the clean hot air after heat exchange is 280° C.-320° C. Preferably, the heat exchange device is a quench cooler.

[0032] It should be noted that the technical route of "low-temperature drying + high-temperature roasting + rapid cooling" is adopted. After the raw materials are mixed and granulated, they are dried at a low temperature of 200°C. The dried balls enter the waterfall rotary kiln, and the expanded clay lightweight aggregate is roasted at a high temperature of more than 1100°C. The exhaust gas from the kiln is dust-removed and rapidly cooled within 2 seconds before being used in ball drying and other processes to prevent the generation and re-synthesis of dioxins.

[0033] In the ceramsite production process of this embodiment, please refer to Figure 1 The temperature of the exhaust gas out of the kiln after heat exchange is 100℃-150℃, and it is discharged after dust removal and wet desulfurization treatment.

[0034] It should be noted that, according to the actual situation, the exhaust gas from the waterfall rotary kiln enters the secondary combustion chamber, SNCR desulfurization device, the first dust collector, the heat exchange device, the second dust collector and the wet desulfurization device in sequence. The first dust collector and the second dust collector are both bag dust collectors. The temperature of the exhaust gas from the second dust collector is lower than 150°C, and the temperature of the exhaust gas from the wet desulfurization device is lower than 120°C. The exhaust gas from the dryer meets the emission standards after passing through the third dust collector, induced draft fan and water scrubber.

[0035] In the ceramsite production process of this embodiment, please refer to Figure 1 In S300, the clean cold air is heat exchanged by the cooler and dust-removed to form clean hot air after heat exchange by the cooler. The clean hot air after heat exchange by the cooler is transported to the dryer. The temperature of the clean hot air after heat exchange by the cooler is 280℃-320℃.

[0036] It should be noted that after the material balls are fully roasted and melted in the waterfall rotary kiln, they fall into the cooler for cooling. The gas temperature entering the dryer through the cooler is lower than 320℃. The cooled ceramsite is sent to the finished product screen through the elevator, and different specifications are screened according to market demand and packaged and sent to different finished product warehouses for storage. In addition, a dust removal mechanism can be set at the finished product screen to remove dust from the formed ceramsite to prevent dust from flying when the ceramsite is screened and filtered.

[0037] In summary, the production process is equipped with a waste heat recycling pipeline. First, the heat exchange device extracts the flue gas heat generated during the roasting process of the waterfall rotary kiln and uses it for drying the raw material balls, so that the drying section does not require an external heat source; second, the waste heat collected by the cooler for cooling the expanded clay is also recovered. After heat balance calculation, in addition to ball drying, it can also be used for workshop heating, bathing and other purposes, thus realizing the efficient utilization of all thermal energy to the greatest extent.

[0038] Under the premise that the water content of the mixture is not higher than 20% and the calcium content of the mixture is not higher than 8%, the inventor conducted an experiment on the proportion of ceramsite formula components and tested the performance of the finished product. The results are as follows: Experiment 1: Gold tailings: bentonite = 95:5, drying temperature is 180℃, roasting temperature is 1300℃, the bulk density of the prepared ceramsite is 1185.3kg / m 3 The water absorption rate in 1 hour is 5.93% and the cylinder pressure strength is 16.81MPa.

[0039] Experiment 2: Graphite tailings: bentonite = 95:5, drying temperature is 180℃, roasting temperature is 1300℃, the bulk density of the prepared ceramsite is 1190.5kg / m 3 The water absorption rate in 1 hour is 0.46% and the cylinder pressure strength is 17.89MPa.

[0040] Experiment 3: Graphite tailings: red mud: municipal sludge = 60:20:20, drying temperature is 180℃, roasting temperature is 1300℃, the bulk density of the prepared ceramsite is 939.18kg / m 3 The water absorption rate in 1 hour is 1.8% and the cylinder pressure strength is 15.44MPa.

[0041] Experiment 4: Graphite tailings: gold tailings: municipal sludge: bentonite = 20:40:35:5, drying temperature is 180℃, roasting temperature is 1300℃, the bulk density of the prepared ceramsite is 1159.68kg / m 3 The water absorption rate in 1 hour is 0.83% and the cylinder pressure strength is 13.57MPa.

[0042] Experiment 5: Graphite tailings: red mud: gold tailings: municipal sludge = 30:25:40:5, drying temperature is 180℃, roasting temperature is 1300℃, the bulk density of the prepared ceramsite is 658kg / m 3 The water absorption rate in 1 hour is 2.94% and the cylinder pressure strength is 12.6MPa.

[0043] From Experiments 1 to 5, it can be seen that when (municipal) sludge and tailings (graphite tailings, gold tailings) are combined as raw materials, the produced ceramsite has excellent performance, not only with low bulk density and low water absorption, but also with high cylinder pressure strength, which meets the use requirements of ceramsite. In addition, in order to provide the lightweight and porous characteristics of ceramsite, red mud is added to the formula of Experiment 5 to reduce the weight of ceramsite and have good thermal insulation effect.

[0044] The present invention has been described in detail above. The above description is only a preferred embodiment of the present invention and should not limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made within the scope of this application should still fall within the scope of the present invention.

Claims

1. A ceramsite production process, characterized in that: The following steps are involved: S100, crushing and grinding the tailings and slag to obtain tailings powder and slag powder with a particle size of no more than 200 meshes, mixing the tailings powder and slag powder with the sludge to obtain a mixture, wherein the moisture content of the mixture is no more than 20%, and the calcium content of the mixture is no more than 8%; S200, the mixture is sent to an aging room for aging, the aged mixture is sent to a granulator for granulation, the granulated raw material balls are sent to a dryer for drying, and the dried material balls are sent to a waterfall rotary kiln for roasting; S300, the molten material balls after high-temperature roasting fall into the cooler for cooling. The cooled expanded clay is screened into different specifications according to market demand and packed and sent to the finished product storage area for storage.

2. A ceramsite production process according to claim 1, characterized in that, In S100, the sludge is red mud, river silt and / or municipal sludge, and its moisture content is not higher than 65%; the tailings are fly ash, coal gangue, gold tailings, iron tailings, graphite tailings and / or molybdenum tailings, and its moisture content is not higher than 3%; the slag is gasified slag, bentonite and / or engineering slag, and the sieve residue of the tailings powder and the slag powder does not exceed 15%.

3. A ceramsite production process according to claim 1 or 2, characterized in that: The sludge needs to be transported to the sludge storage workshop by conveying equipment for standby use. The whole process is sealed and slightly negative pressure conveyed. The sludge in the sludge storage workshop is dispersed by the disperser and sent to the batching hopper, which measures and discharges the sludge. The tailings powder is pumped to the powder silo for storage and is transported in a sealed manner throughout the entire process. The tailings powder in the powder silo is sent to the metering scale for controlled metering via a closed screw conveyor.

4. A ceramsite production process according to claim 1, characterized in that: In S200, the mixture is stirred and then sent to an aging room for 48-72 hours.

5. A ceramsite production process according to claim 4, characterized in that, In S200, the raw material balls after granulation are firstly sent to a shaping machine for shaping, and the moisture content of the shaped raw material balls is not higher than 20%. The shaped raw material balls are then sent to a dryer for drying.

6. A ceramsite production process according to claim 5, characterized in that: The drying temperature of the dryer is 150°C-200°C, the moisture content of the dried pellets is not higher than 2%, and the exhaust gas discharged from the dryer meets the emission standards after dust removal, wet desulfurization and wet electrostatic dust removal.

7. A ceramsite production process according to claim 6, characterized in that: The calcination temperature of the waterfall rotary kiln is 1100-1500°C, the exhaust gas temperature of the waterfall rotary kiln is 800°C-850°C, the exhaust gas is treated with SNCR denitrification and then dust removed before being sent to the heat exchange device, and the clean hot air after heat exchange is sent to the dryer.

8. A ceramsite production process according to claim 7, characterized in that: The clean cold air in the heat exchange device completes heat exchange with the kiln exhaust gas within 2 seconds to form clean hot air after heat exchange, and the temperature of the clean hot air after heat exchange is 280°C-320°C.

9. A ceramsite production process according to claim 7, characterized in that: The temperature of the exhaust gas out of the kiln after heat exchange is 100℃-150℃, and it is discharged after dust removal and wet desulfurization treatment.

10. A ceramsite production process according to claim 6, characterized in that: In S300, the clean cold air is heat exchanged by the cooler and dust removed to form clean hot air after heat exchange by the cooler. The clean hot air after heat exchange by the cooler is transported to the dryer. The temperature of the clean hot air after heat exchange by the cooler is 280℃-320℃.

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