AU2017424295A1

AU2017424295A1 - Material drying method

Info

Publication number: AU2017424295A1
Application number: AU2017424295A
Authority: AU
Inventors: Pengyun Wang
Original assignee: Yunnan Zhongyi Dingdong Energy Technology Development Co Ltd
Current assignee: Yunnan Zhongyi Dingdong Energy Technology Development Co Ltd
Priority date: 2017-07-18
Filing date: 2017-12-29
Publication date: 2020-02-06
Anticipated expiration: 2037-12-29
Also published as: WO2019015263A1; AU2017424295B2; CN107388757B; CN107388757A

Description

MATERIAL DRYING METHOD

FIELD OF THE INVENTION

The invention relates to the field of the method of drying materials, in particular relates to drying highly watery and highly viscous materials.

BACKGROUND OF THE INVENTION

With the development of China's industrialization, China's environmental pollution has become more and more seriously, and the environmental bearing capacity has been increasingly challenged.

First of all, the sludge formed after the treatment of urban domestic sewage generally has a moisture content of about 80%, which either rich in nutrients such as organic matter and the like, or contains a certain amount of heavy metals and harmful substances such as viruses, pathogens, parasite eggs and the like. Improper disposal of sludge will result in seriously secondary environmental pollution. At present, there are three main methods for the sludge treatment abroad: 1. Land fill. In the past, many developed countries have adopted the method of land fill to treat the sludge, and it accounts for a quite large proportion (about 40%). Land fill is also the main method in China. The treatment process of this method is very simple, especially suitable for the sludge with poor quality, however, the site and a large amount of freight are required, and the foundation needs to be treated with anti-seepage to avoid polluting the groundwater and dissipating the odor. In addition, the land suitable for filling is decreasing year by year. 2. Dumping into oceans. In some countries and regions close to the sea, large-scale sewage treatment plants often discharge liquid sludge directly into the sea or send dewatered sludge directly into the sea. This is a convenient and economical treatment method, but this method will harm the marine ecosystem and the human food chain, causing harm on a global scale. In 1988, the United States banned the dumping of sludge into the ocean which was completely banned in 1991. It was pointed out in the “Directive Concerning Urban Wastewater Treatment” issued by the European Community in May 1991 that, sludge should not be disposed in water bodies since December 31, 1998. 3. Incineration method. In Europe and the United States, in the case of high levels of heavy metals or other toxic substances in sludge which are not suitable for agricultural use, incineration is often used. The sludge is incinerated to produce a sterile, odorless inorganic residue and greatly reduces the volume. It is a reliable and effective sludge disposal method. Sludge incineration ash can be effectively used as the building materials such as asphalt fillers, lightweight substrates and the like, for example, the main raw material for making bricks. The heat generated by the combustion can be used to supply the electricity. However, the costs of the equipment and operation for the incineration method are expensive and it is likely to cause air pollution. There is still about 1/3 solid weight of the waste remaining in the form of ash.

All of the above methods for the treatment of municipal sludge cannot achieve comprehensive utilization of the sludge, and there are certain social and environmental problems. So, they are not the best way to treat the sludge. For a developing country like China, comprehensive utilization, especially agricultural use, is undoubtedly a better choice. To realize the effective use of the sludge, turning the waste into a treasure, and making it a resource and generating economic benefits will become the development trend of sludge treatment.

In the sludge of the municipal living sewage treatment, the water content is about 80%, and there are large amounts of organic matter. The process of using the sludge to manufacture organic compound fertilizer is to dry the sludge at high temperature, kill the bacteria and eggs, preserve the organic components from being damaged and remove the harmful bacteria (performing harmless treatment), access the beneficial bacteria to culture, and eliminate the sludge odor, increase the nutrient elements in the sludge, and further add the effective ingredients such as nitrogen, phosphorus and potassium to increase the nutrient content in the sludge; through the processes of granulation, low-temperature drying and the like, to make the sludge biologically active, fully nutrient, and pollution-free organic compound fertilizer. Therefore, it has found a good way for the sludge after water treatment, and increasing the economic and social benefits of the sewage treatment plant and equipment manufacturers, turning the sludge from waste into a treasure, reducing the environmental sludge, protecting the natural environment on which human depends, and it is conducive to the development of ecological agriculture either.

However, the key to turning waste sludge into wealth relies on the drying equipments and drying methods. The current drying methods cannot achieve high efficiency, high dehydration rate, and the safety cannot be guaranteed.

Secondly, mineral resources are either one of the important material foundations for human survival and development or a premise and guarantee for social development. At present, in China, 95% of energy and 85% of raw materials come from mineral resources. With the rapid development of China's economy, the demand for mineral resources is increasing. The development of a large number of mineral resources has not only brought abundant material and raw materials, but also produces a large number of tailings. Therefore, tailings utilization is a key issue for sustainable development of mining enterprises.

China is a large country producing non-ferrous metals. The tailings amount account for 70% ~ 95% of the selected ore. The tailings are stored more than 2.2 billion tons and grow at 140 million tons per year. The tailings dams are rarely operated normally. The average utilization rate of the tailings is 8.2%. Therefore, starting from the actual situation of China's non-ferrous metal tailings resources, vigorously developing the comprehensive utilization of tailings resources is of great significance to improve the ecological environment and resource utilization. It is the most environmentally friendly use for the use of non-ferrous metal tailings after being dried as building materials and the like.

However, the key to non-ferrous metal tailings is the drying equipment and the drying methods. The current drying methods cannot achieve high efficiency and high dehydration rate, and safety cannot be guaranteed.

In addition, China takes coal as basic energy, with the increasing environmental pollution problems and shortages of the resource, the efficient use of coal is urgent. China is still in the historical stage of industrialization and accelerated urbanization. There is still a room for growth in the total energy demand. Coal accounts for more than 90% of China's fossil energy resources. For a long period of time, the dominant energy status of coal will not change, and the ecological and environmental constraints of the coal development will be increasingly strengthened. The clean and high efficient development and the utilization of coal has become the primary task of energy transformation and development. The development and industrialization of coal grading and grading cascade utilization technology and the development of green and high efficient utilization technology of the low-cost coal are listed as national energy development strategic action plans.

At present, China's utilization of high-moisture, high-viscous coal (coal slime, low-rank coal, etc.) is lower, but the upgrading utilization of high-moisture, high-viscous coal (coal slime, low-rank coal, etc.) has been listed in the 13 Five-Year Plan of National Energy, and the industry will be supported by national policies for a long time. The key process for the upgrading of coal is drying, because the calorific value of coal is closely related to the water content. As long as the moisture is reduced, the calorific value will increase accordingly.

Taking coal slime as an example, coal slime, as a by-product of the raw coal washing process, has been regarded as a waste that is considered to be difficult to use because of its high moisture, high viscosity and low calorific value. In fact, the origin why coal slime is difficult to use lies in that its moisture is high, and for each percentage of moisture reduction, the calorific value will increase by 60 kcal. The calorific value of coal slime with 30% moisture is generally 2000-4000 kcal. If it is dehydrated by 15% further, the calorific value will increase by more than 900 kcal and reach 3000-5000 kcal. It meets the quality requirements of commercial power coal and can be sold individually or mixed with medium coal (blended coal) to make the price of coal slimes increased from the price of coal preparation waste or by-products to the price of commercial thermal coal.

There are currently three ways to dispose the coal slime:

(1) In most areas, because of the lack of sales, the coal slime is directly piled up in natural sinkholes or ravines. The coal slime still contains about 30% of water upon pressure filtration, and it is easy to liquefy and pollute the surrounding environment. After drying, it will fly up in the wind and flow around when meeting the water, polluting the roads, the land and the rivers, and may also directly infiltrate the ground and pollute the groundwater. This simple disposal method not only makes the enterprises bear relatively higher economic costs such as land fees, transportation fees, sewage charges and the like, but also pollutes the environment. The social cost caused by polluting the water bodies is huge.

(2) In some areas, coal slime is mixed into the coal and be sold together. Doing so will increases the ash and moisture of commercial coal, lowers the quality of commercial coal, the transportation moisture either increases transportation costs, or causes coal slime agglomeration and lead to the problems such as clogging and unloading difficulties and the like, even frozen vehicles when there is a low temperature in winter, which will seriously affect the transportation efficiency. In fact, such disposal method reduces the washing effect of raw coal greatly.

(3) In recent years, a number of power plants with comprehensive utilization of coal gangue and coal slime have been developed and a part of the coal slime is treated by burning. However, 30% of water-containing in coal slurry is too high in moisture for the pulverized coal boilers in power plant. The latent heat of gasification consumes a large amount of heat, which seriously reduces the thermal efficiency of the boiler, increases the operating costs and increases the emissions amount meanwhile, and increases the environmental protection investment.

The above three disposal manners, either on-site storage, or the sales with water, or burning with water, all of which are the treatments for consuming the coal slime itself, which has no economic benefits and further cause resources waste.

Based on the above, high-water-content and high-viscous coal (coal slime, low-rank coal, etc.) has always been difficult to be utilized. The key lies in that its water content is over high which affects the heat efficiency and the key to improve quality lies in drying. As we all know, the drying of materials, especially the drying of coal, has the following major problems: 1. If both the temperature and oxygen content are too high, the coal will be pyrolyzed (combustion reaction) during the drying process, which affects the calorific value of the coal; 2. If the three parameters of “dust concentration, oxygen content, and temperature” are not well controlled, a fire and explosion will occur.

3. Generally, the existing drying methods or devices can only be used to dry a single material with poor versatility and low drying rate.

At present, there are many domestic drying processes and equipments. In the field of coal slime in the coal industry, they are mainly the three classes of slime drum drying process, tunnel drying process (including flap dryer and mesh belt dryer) and airflow drying process.

Drum dryer is one of the earliest drying equipment. It is not only used for drying coal, but also has been widely used in the field of metallurgy, building materials, chemical industry and the like. The disadvantage of the drum drying process machine is that: the drying temperature of this type of drying process is above 700 °C, which can not effectively control the oxygen content in the drying process; the temperature is much higher than the ignition point of lignite and long flame coal 278°C; the drying time is relatively long; it is not suitable for the drying of lignite and long-flame coal slime; and physical reactions will occur which will affect the using performance of coal. Moreover, this kind of drying equipment used for drying the coal slime which can only increase the calorific value of 400-600 kcal/kg, with a dehydration rate less than 30% and without a dust recovery function.

The tunnel drying process is suitable for the drying of block and strip materials. There is a flap type device and a metal mesh belt type device. After the slime is extruded into a strip, it can be dried on a metal mesh belt dryer. The disadvantage of this drying process is that it is not suitable for the drying of loose coal slime and the drying efficiency is low.

The airflow drying process utilizes the direct contact between the heating medium (hot air, flue gas, etc.) and the wet material particles, and suspends the solid particles in the heating medium fluid, which strengthens the mass and heat transfer process. It belongs to “instant drying” and is generally applied to the drying of bulk materials. For the drying of coal slime in the coal industry, it is also necessary to “granulate” or “mold” firstly. The disadvantage of this drying process is as follows: this kind of drying equipment is used for drying slime, which can only increase the calorific value of 200-400kcal/kg, the dehydration rate is less than 7%, it has no dust recovery function; and the industrial practice effect for drying the slime is not good. Generally, the process is not adopted to dry the coal slime.

There are also technical barriers to the utilization of low-rank coal such as non-caking coal, lignite and the like. Non-caking coal is a kind of low-to-medium metamorphic bituminous coal. Its silk carbonization component is generally high in content and it is high in moisture. Without drying and upgrading, its utilization value is very low.

The existing lignite drying processes mainly include cooking drying process and airflow reverse drum drying process. Detailed description is as follows: CN102051246A discloses a cooking drying process for lignite. The specific steps are: a. using the hot water with a temperature greater than 30 °C to perform the washing and leaching treatment to the raw material of lignite granule to remove the dust, a part of ash and a part of sulphur contained in the raw material of lignite granule, and at the same time obtain the preliminarily upgraded lignite granule; next, b. making the said preliminarily upgraded lignite granules to enter into the digester, and then using the steam to boil the lignite granule under the condition of pressure for a certain time to obtain the further upgraded lignite granules, and the liquid water obtained during the cooking process is discharged; and then, c. making the digester depressurized and then the further upgraded lignite particles are discharged therefrom. However, this method has a low dehydration rate and a low drying rate without industrial use value. CN103013615A discloses a device and method for high efficient drying and upgrading the lignite. The coal-burning from the fuel bunker and the pulverized coal separated from the cyclone duster and the electrostatic duster are burned in a hot air furnace to generate flue gas with a high temperature of 700-900 °C. Used as a drying heat source, the high temperature flue gas is sent to the drum dryer, and flows from the bottom to the top along the inclined drum dryer for drying the raw lignite in the drum dryer. Convective heat exchanged is performed between high temperature flue gas and raw lignite in the drum dryer. After drying the raw lignite, the high temperature flue gas becomes the low temperature flue gas carrying pulverized coal in the raw material lignite. The temperature of the low temperature flue gas is 90-120 °C. The low temperature flue gas is output from the drum dryer. However, in this kind of drying process, the oxygen content can not be controlled, it is easy to hang materials, lignite and gas flow are retrograde, the residence time of the lignite in the drying device is too long, which lead the lignite easy to pyrolyze, and the drying rate is not high, it is not suitable for industrial promotion.

Based on the above, the motivation for the invention is to study the relationship among various parameters through a large number of experiments and researches, and provide a method for drying materials with high dehydration rate, simple for equipment, safe operation, high drying efficiency, good versatility and environmental protection.

SUMMARY OF THE INVENTION

The present invention aims at overcoming the shortcomings of the prior art and provide a method for drying the materials with high dehydration rate, simple for equipment, safe operation, high drying efficiency and good versatility as well as environmental protection. The drying method of the present invention has a good versatility, which is suitable for drying various materials such as low-rank coal, coal slime, municipal sludge or non-ferrous metal tailings and the like.

The invention provides a method for drying the materials, and the technical solution is as follows.

A method for drying the materials includes the following steps: introducing the hot airflow with a temperature of 200-1500 degrees Celsius and an oxygen content of less than 12% into the cavity of a drying device from an air inlet, an induced draft fan is provided at the tail end of an air outlet to generate a negative pressure of 100-6000 Pa in the cavity of the drying device, and the flow rate of the hot airflow in the cavity is 2-24 m/s; rotating devices are provided at the bottom of the cavity, the setting position of the inlet of the drying device is higher than that of the top of lifting teeth on the rotating devices, the rotational speed of the rotating devices is 50-500 rpm, the materials and a hot airflow enter into the cavity concurrently, the lifting teeth crush and spray the materials into the hot airflow, the drying time of the materials in the entire cavity is 1-20 s; and the materials are dried by the hot airflow and then discharged from the drying device.

Preferably, the cavity of the drying device is divided into a plurality of chambers by the baffles, and the materials are disaggregated, sprayed and diffused in the chamber through the lifting teeth, the disaggregated materials are dried by the hot airflow in the chamber, gradually flow to the next chamber, andflnally discharged through the discharge port.

Preferably, the cavity of the drying device is divided into a plurality of chambers by the staggerly arranged baffles and the windshileds so that the directions of hot airflow and the materials in the chambers are S-shaped.

Preferably, the width of the last chamber is greater than that of the other chambers so that the flow rate of the materials is reduced.

Preferably, the materials are collected through the discharge port, a separator of flowing direction of the flue gas and a dust collector.

Preferably, the temperature at the air outlet of the hot airflow is 60-200 degrees Celsius.

Preferably, the granularity of the materials after drying is 0.01-15 mm.

Preferably, the temperature of the hot airflow at the air inlet has a temperature of 800-1100 degrees Celsius and an oxygen content of less than 8%, the negative pressure of the drying device is 900- 6000Pa, the flow rate of the hot airflow in the cavity is 8-18m/s; the rotational speed of the rotating devices is 100-400 rpm, and the drying time of the materials in the entire cavity is 1-5 s.

Preferably, the hot airflow at the air inlet has a temperature of 600-900 degrees Celsius and an oxygen content of less than 11%, the negative pressure of the drying device is 900-6000 Pa, the flow rate of the hot airflow in the cavity is 8-14 m/s; the rotational speed of the rotating device is 100-400 rpm, and the drying time of the materials in the entire cavity is 1-5 st.

Preferably, the said drying method is used for drying lignite, long flame coal, non-caking coal, weakly caking coal, blast furnace injection coal, gas coal, gas fat coal, meager lean coal, lean coal, fat coal, anthracite, coal slime, municipal sludge or non-ferrous metal tailings.

Preferably, the said drying method is used for drying low rank coal, and the low rank coal is any one of lignite, long flame coal, non-caking coal, weakly caking coal, blast furnace injection coal, gas coal, gas fat coal, meager lean coal, lean coal, fat coal and anthracite. A method for drying low-rank coal, wherein the temperature of the hot air flow at the air inlet is 901-1100 °C, the oxygen content is less than 8%, the negative pressure of the drying device is 900-6000 Pa, the flow rate of the hot air flow in the cavity is 8- 18m/s; the rotational speed of the rotating device is 100-400 rpm; and the drying time of the materials in the io entire cavity is 1-5 s.

Preferably, the said drying method is used to dry the coal slime. A method for drying coal slime, wherein the temperature of the hot air flow at the air inlet is 800-1100 degree Celsius, the oxygen content is less than 8%, the negative pressure of the drying device is 900-6000 Pa, the flow rate of the hot air flow in the cavity is 8-18 m/s; the rotational speed of the rotating device is 100-400 rpm, and the drying time of the materials in the entire cavity is 1-5 s.

Preferably, the said drying method is used to dry municipal sludge. A method for drying municipal sludge, wherein the temperature of the hot air flow at the air inlet is 900-1500 degree Celsius, the oxygen content is less than 10%, the negative pressure of the drying device is 900-6000 Pa, the flow rate of the hot airflow in the cavity is 8-18m/s; the rotational speed of the rotating device is 100-400 rpm, and the drying time of the materials in the entire cavity is 1-5 s.

Preferably, the above drying method is used to dry non-ferrous metal tailings. A method for drying non-ferrous metal tailings, wherein the temperature of the hot air flow at the air inlet is 700-1500 degree Celsius, the oxygen content is less than 10%, the negative pressure of the drying device is 900-6000 Pa, and the flow rate of the hot air flow in the cavity is 8-14 m/s; the rotational speed of the rotating device is 100-400 rpm, and the drying time of the materials in the entire cavity is 1-5 s.

Glossary;

Disaggregation: The process by which large particles are broken up into small particles.

Mass heat exchange: the process of inter-heat transfer and mass change, the process specific to the present invention is that the hot airflow conducts heat to the materials to heat up the materials the evaporation of water is accompanied meanwhile, and the materials are dried.

The implementations of the present invention include the following beneficial effects:

In the present invention, by defining the parameters such as the negative pressure value, the temperature, the oxygen content and the like in the cavity of the drying device, making the dehydration rate of the drying method defined in the present invention is greater than 60%, no explosion will occur and the workshop will run safely. The drying rate is high and can reach 600-750 kg-H₂0/m h (600-750 kg of water can be removed per hour per cubic meter of dry space). Using this method, 30-80 cubic meters of the materials can be dried per hour. The moisture content of the dried coal is well controlled, and the granularity of the materials is uniform, which effectively guarantees the quality of the dried product. The definition in the present invention makes the drying time of the materials in the entire cavity is quite short, which can ensure a high dehydration rate without causing the materials to pyrolyze (combustion reaction).

In the present invention, the setting of the parameters such as the drying time, the hot air temperature and the negative pressure of the cavity makes the materials quickly dried and will not stick to the casing of the chamber.

When the drying method of the present invention is used for drying the coal, the reasonable setting of the parameters such as the drying temperature, the negative pressure, the flow rate, and the oxygen content makes the combustible component of the coal will not volatilize or bum and the explosion critical value cannot be reached, which will affect the calorific value of the coal.

THE DESCRIPTION OF THE DRAWINGS

FIG. 1 is the flow chart of the method for drying materials according to Examples of the present invention.

FIG. 2 is the structural schematic of the drying device according to Examples of the present invention.

FIG. 3 is the schematic taken along A-A Section in FIG. 2.

FIG. 4 is the structural schematic of the drying device including baffles according to Examples of the present invention.

FIG. 5 is the structural schematic of the drying device including baffles plate and windshields according to Examples of the present invention.

FIG. 6 is another flow chart of the method for drying materials according to Examples of the present invention.

FIG 7 is the structural schematic of the drying device discharging materials with hot air flow according to Examples of the present invention.

In the figures: 1, drive device; 2, rack; 3, casing; 4, lifting teeth; 5 drive shaft; 6, air inlet; 7, inlet; 8, air outlet; 9, discharge port; 10, the flow curve of hot air flow; 11, baffle; and 12, windshield.

DETAILED EMBODIMENTS

The present invention will be described in details below with reference to the Examples and the accompanying drawings. It should be to be noted that the described Examples are only intended to facilitate the understanding to the present invention and but do not limit it in any way.

Example 1

A method for drying coal slime provided in this Example, as shown in FIG

1- FIG.3, including the following steps: using a gas heating device (commonly, such as a hot air furnace) to generate a hot air flow (flue gas); introducing the hot air flow with a temperature of 200-1500 degree Celsius (being 901 degree Celsius in this Example) and an oxygen content of less than 10% into the cavity of the drying device from the air inlet 6; the induced draft fan is provided at the end of the air outlet 8 (not shown in figures), making the cavity of the drying device to generate a negative pressure of 100-6000 Pa (being 4000 Pa in this Example), and the flow rate of the hot airflow in the cavity is 8-14 m/s (being 10 m/s in this Example); the setting position of the inlet 7 of the drying device needs to be higher than that of the top of the lifter tooth 4, and it is set on the top of the shell in this Example. Such setting makes the materials and the hot air flow enter into the cavity co-currently. Specifically, the inlet 7 and the air inlet 6 can be set as shown in FIG. 2, and the air inlet 6 and the inlet 7 can also be set on one side of the casing simultaneously, as long as the materials and the hot airflow can be collected before being thrown by the lifting teeth 4, all of which belongs to the manner of “the materials and the hot airflow enter into the cavity co-currently” as mentioned in this Example. A rotating device is provided at the bottom of the cavity and the rotating device is provided with lifting teeth 4 and driven by the driving shaft 5 of the driving device 1. The rotating device and the driving device are arranged on the rack 2 on which the casing 3 is provided. The rotational speed of the rotating device is 50-500 rpm (being 200 rpm in this Example). The materials are sprayed by the lifting teeth 4 on the rotating device and diffused into the hot air flow. The drying time of the materials in the entire cavity is l-5s (being 5s in this Example). The materials are dried by the hot airflow (mass heat exchange) and then discharged from the drying device. The temperature of the hot air at the air outlet 8 is 120-200 degree Celsius. The hot airflow direction curve 10 is shown in FIG 2. In this Example, by defining the parameters such as the negative pressure value, the temperature, the oxygen content and the like, the dehydration rate of the drying method defined by the present invention is greatly improved and the explosion threshold value cannot be reached so that no explosion will occur, the workshop will run safely and the drying rate is high. The moisture content of the dried coal is better controlled, and the granularity of the materials is uniform, which effectively guarantees the quality of the dried product. The definition of the present invention makes the drying time of the materials in the entire cavity short, which can ensure a high dehydration rate without causing the pyrolysis (combustion reaction) of the materials, and the materials are dried quickly without sticking to the shell of chamber.

Preferably, the materials are collected through the discharge port 9, a separator of flowing direction of the flue gas and the dust collector. The width of the last chamber is greater than that of the other chambers so that the flow rate of the materials is reduced, and majority of the coal slime is discharged from the discharge port 9.

In this Example, the rotational speed of the drive shaft can be adjusted by the frequency converter to adjust the spraying speed of the coal slime material in the cavity, thereby adjust the temperature of the hot airflow and the internal oxygen content in the heat exchange process. In the actual production process, it is also matched with the value of wind pressure of the induced draft fan, which can improve the heat exchange efficiency of the materials in the space of the chamber and reduce the resistance of the materials along the movement curve during the deaggregation process.

After coal mining, a coal washing process must be carried out. The method of the present Example is used for drying the coal slurry produced by the coal washing. It can improve the washing process of the coal preparation plant, realize the second leap from the closed-loop recycling of washing water to the coal slime recycling, and solve the secondary pollution problem such as “loss in water and flying in the wind” in the mining environment caused by the accumulation of the coal slime products in the open air completely. It reduces the areas of the waste storage and the enterprises’ sewage charges, and thereby increase the economic benefits of the enterprises. In addition, it solves the passive situation that the poor sales of the coal slime due to seasonal changes, or the production is affected by treatment difficulty. After the coal is dried, the Moisture is reduced, which can reduce the cost of transporting the moisture and avoid the problems such as traffic jams, the car freezing and the like. To the end user, it can further improve the thermal efficiency of the boiler, reduce the emissions and reduce the investment on the environmental protection.

The data for drying the coal slime using the drying method of this Example is shown in Table 1.

Table 1. The data of dried coal slime in Example 1

Drying rate	600kgH₂0/m³h
Increased calorific value	900kcal/kg

Dehydration rate	About 60%
Granularity of coal slime	<10mm
Processing capacity for single device per hour (wet basis)	50 cubic meter

Example 2

The Example provides a method for drying coal slime, and the distinction between it and Example 1 is as follows: the temperature of the hot air flow at the air inlet is 1000 degrees Celsius, the oxygen content is less than 8%; the 5 negative pressure of the drying device is 4500 Pa; the flow rate of the hot air flow in the cavity is 10 m/s; the rotational speed of the rotating device is 200 rpm; and the drying time of the materials in the entire cavity is 3 s. Referring to FIG. 4, the cavity of the drying device of the present Example is divided into a plurality of chambers by the baffles 11. When the materials are disaggregated io and sprayed by the lifting teeth and dispersed in the chamber, the disaggregated materials are dried in the chamber (mass heat exchange) with the hot airflow and then flows gradually to the next chamber and are discharged through the discharge port finally. The baffles 11 are disposed at the bottom of the casing 3.

The hot airflow direction curve 10 is shown in FIG. 4. The method of this

Example is applicable to drying low rank coal, municipal sludge or non-ferrous metal tailings equally. The same parts as those in Example 1 will not be described in detail in this Example.

Table 2. The data of dried coal slime in Example 2

Drying rate	600kgH₂0/m³h
Increased calorific value	lOOOkcal/kg
Dehydration rate	About 65%
Granularity of coal slime	<10mm
Processing capacity for single device per hour (wet basis)	50 cubic meter

Example3

This Example provides a method for drying coal slime, and the distinction between it and Example 1 is as follows. The hot air flow at the air inlet has a temperature of 1200 degree Celsius and an oxygen content of less than 8%. The negative pressure of the drying device is 4000 Pa. The flow rate of the hot airflow in the cavity is 10 m/s. The rotational speed of the rotating device is 200 rpm. The drying time of the materials in the entire cavity is 3 s. Referring to FIG. 5, the cavity of the drying device is divided into a plurality of chambers by the staggerly arranged baffles 11 and windshields 12, such that the direction of the hot airflow and the materials in the chambers is S-shaped, the mass heat exchanges sufficiently and the thermal efficiency is improved. The hot airflow direction curve 10 is shown in FIG. 5. The baffles 11 are disposed at the bottom of the casing 3, and the windshields 12 are disposed at the top of the casing. The method of this Example is applicable to drying low rank coal, municipal sludge or non-ferrous metal tailings equally. The same parts as those in Example 1 will not be described in detail in this Example.

The lower baffles divide the casing into a plurality of chambers. Until the granularity and the humidity reach a certain degree, the materials will enter into the latter chamber. Due to the heavier self-weight of the materials with large granularity and high humidity, they cannot move with the hot air and enter into the next chamber but continue to fall into the current chamber. They are stirred by the lifting teeth to achieve upward spraying and achieve the continuous crushing of the large particles of the coal slime. The crushing is concurrently achieved by the colliding of the lifting teeth, the lower baffle and the particles. After the transition of a plurality of chambers, they finally arrive at the air closer of the discharge to ensure that the final products have a uniform granularity and the humidity meets the requirements.

The upper baffles and lower baffles make the hot air and the materials constitute S-shaped direction, the exchange efficiency is high and the energy consumption is small.

Table 3. Data of dried coal slime for Example 3

Drying rate	600kgH₂0/m³'h
Increased calorific value	1200kcal/kg
Dehydration rate	About 70%
Granularity of coal slime	<10mm
Processing capacity for single device per hour (wet basis)	50 cubic meter

Example 4

A method for drying lignite provided in this Example, as shown in FIG. 6 and FIG.7, including the following steps: using a gas heating device (commonly, such as a hot air furnace) to generate a hot air flow (flue gas); introducing the hot air flow with a temperature of 200-1500 degree Celsius (being 900 degree Celsius in this Example) and an oxygen content of less than 8% into the cavity of the drying device from the air inlet 6; the induced draft fan is provided at the end of the air outlet 8 (not shown in figures), making the cavity of the drying device to generate a negative pressure of 100-6000 Pa (being 4000 Pa in this Example), and the flow rate of the hot airflow in the cavity is 8-14 m/s (being 10 m/s in this Example); the setting position of the inlet 7 of the drying device needs to be higher than that of the top of the lifter tooth 4, and it is set on the top of the shell in this Example. Such setting makes the materials and the hot air flow enter into the cavity co-currently. Specifically, the inlet 7 and the air inlet 6 can be set as shown in FIG. 7, and the air inlet 6 and the inlet 7 can also be set on one side of the casing simultaneously, as long as the materials and the hot airflow can be collected before being thrown by the lifting teeth 4, all of which belongs to the manner of “the materials and the hot airflow enter into the cavity co-currently” as mentioned in this Example. A rotating device is provided at the bottom of the cavity and the rotating device is provided with lifting teeth 4 and driven by the driving shaft 5 of the driving device 1. The rotating device and the driving device are arranged on the rack 2 on which the casing 3 is provided. The rotational speed of the rotating device is 50-500 rpm (being 200 rpm in this Example). The materials are sprayed by the lifting teeth 4 on the rotating device and diffused into the hot air flow. The drying time of the materials in the entire cavity is l-5s (being 3s in this Example). The materials are dried by the hot airflow (mass heat exchange) and then discharged from the drying device. The temperature of the hot air at the air outlet 8 is 120-200 degree Celsius. The hot airflow direction curve 10 is shown in FIG. 7. In this Example, by defining the parameters such as the negative pressure value, the temperature, the oxygen content and the like, the dehydration rate of the drying method defined by the present invention is greatly improved and the explosion threshold value cannot be reached so that no explosion will occur, the workshop will run safely and the drying rate is high. The moisture content of the dried coal is better controlled, and the granularity of the materials is uniform, which effectively guarantees the quality of the dried product. The definition of the present invention makes the drying time of the materials in the entire cavity short, which can ensure a high dehydration rate without causing the pyrolysis (combustion reaction) of the materials, and the materials are dried quickly without sticking to the shell of chamber..

Preferably, the cavity of the drying device is divided into a plurality of chambers by the staggerly arranged baffles and windshileds, so that the directions of both the hot airflow and the materials in the chambers are S-shaped, the mass and heat exchanges sufficiently and the thermal efficiency is improved. The baffles are disposed at the bottom of the casing 3, and the windshields are disposed at the top of the casing. The materials are all carried away with the hot airflow, and then collected through a separator of flowing direction of the flue gas and the dust collector. The width of the last chamber is greater than that of the other chambers so that the flow rate of material is reduced. Most of the coal slimes are discharged from the discharge port 9.

Table 4. The data of dried lignite in Example 4

Drying rate	600 kgH₂0/m³ h
Increased calorific value	2500 kcal/kg
Dehydration rate	About 75%
Granularity of coal slime	< 3 mm
Processing capacity for single device per hour (wet basis)	35 cubic meter

Example 5

A method for drying long frame coal provided in this Example, as shown in FIG.1- FIG.3, including the following steps: using a gas heating device (commonly, such as a hot air furnace) to generate a hot air flow (flue gas); introducing the hot air flow with a temperature of 200-1500 degree Celsius (being 900 degree Celsius in this Example) and an oxygen content of less than 10% into the cavity of the drying device from the air inlet 6; the induced draft fan is provided at the end of the air outlet 8 (not shown in figures), making the cavity of the drying device to generate a negative pressure of 100-6000 Pa (being 4000 Pa in this Example), and the flow rate of the hot airflow in the cavity is 8-14 m/s (being 10 m/s in this Example); the setting position of the inlet 7 of the drying device needs to be higher than that of the top of the lifter tooth 4, and it is set on the top of the shell in this Example. Such setting makes the materials and the hot air flow enter into the cavity co-currently. Specifically, the inlet 7 and the air inlet 6 can be set as shown in FIG. 2, and the air inlet 6 and the inlet 7 can also be set on one side of the casing simultaneously, as long as the materials and the hot airflow can be collected before being thrown by the lifting teeth 4, all of which belongs to the manner of “the materials and the hot airflow enter into the cavity co-currently” as mentioned in this Example. A rotating device is provided at the bottom of the cavity and the rotating device is provided with lifting teeth 4 and driven by the driving shaft 5 of the driving device 1. The rotating device and the driving device are arranged on the rack 2 on which the casing 3 is provided. The rotational speed of the rotating device is 50-500 rpm (being 200 rpm in this Example). The materials are sprayed by the lifting teeth 4 on the rotating device and diffused into the hot air flow. The drying time of the materials in the entire cavity is l-5s (being 3s in this Example). The materials are dried by the hot airflow (mass heat exchange) and then discharged from the drying device. The temperature of the hot air at the air outlet 8 is 120-200 degree Celsius. The hot airflow direction curve 10 is shown in FIG. 2. In this Example, by defining the parameters such as the negative pressure value, the temperature, the oxygen content and the like, the dehydration rate of the drying method defined by the present invention is greatly improved and the explosion threshold value cannot be reached so that no explosion will occur, the workshop will run safely and the drying rate is high. The moisture content of the dried coal is better controlled, and the granularity of the materials is uniform, which effectively guarantees the quality of the dried product. The definition of the present invention makes the drying time of the materials in the entire cavity short, which can ensure a high dehydration rate without causing the pyrolysis (combustion reaction) of the materials, and the materials are dried quickly without sticking to the shell of chamber.

Preferably, the materials are collected through the discharge port 9, a separator of flowing direction of the flue gas and the dust collector. The width of the last chamber is greater than that of the other chambers so that the materials flow rate is reduced, and majority of the coal slime is discharged from the discharge port 9.

The drying device of this Example can also be shown in FIG. 4, the cavity of the drying device is divided into a plurality of chambers by the baffles, when the materials are disaggregated and sprayed by the lifting teeth and dispersed in the chamber, the disaggregated materials are dried in the chamber (mass heat exchange) with the hot airflow and then flows gradually to the next chamber and are discharged through the discharge port finally. Besides, the drying device of this Example can be shown in FIG. 5, the cavity of the drying device is divided into a plurality of chambers by the staggerly arranged baffles and windshileds, so that the directions of both the hot airflow and the materials in the chambers are S-shaped, the mass and heat exchanges sufficiently and the thermal efficiency is improved.

Table 5. The data of dried long frame coal in Example 5

Drying rate	600 kgH₂0/m³ h
Increased calorific value	900 kcal/kg
Dehydration rate	About 50%
Granularity of coal slime	< 6 mm
Processing capacity for single device per hour (wet basis)	50 cubic meter

Example 6

A method for drying non-caking coal provided in this Example, as shown in FIG. 1- FIG.3, including the following steps: using a gas heating device (commonly, such as a hot air furnace) to generate a hot air flow (flue gas); introducing the hot air flow with a temperature of 200-1500 degree Celsius (being 1000 degree Celsius in this Example) and an oxygen content of less than 10% into the cavity of the drying device from the air inlet 6; the induced draft fan is provided at the end of the air outlet 8 (not shown in figures), making the cavity of the drying device to generate a negative pressure of 100-6000 Pa (being 4000 Pa in this Example), and the flow rate of the hot airflow in the cavity is 8-14 m/s (being 10 m/s in this Example); the setting position of the inlet 7 of the drying device needs to be higher than that of the top of the lifter tooth 4, and it is set on the top of the shell in this Example. Such setting makes the materials and the hot air flow enter into the cavity co-currently. Specifically, the inlet 7 and the air inlet 6 can be set as shown in FIG. 2, and the air inlet 6 and the inlet 7 can also be set on one side of the casing simultaneously, as long as the materials and the hot airflow can be collected before being thrown by the lifting teeth 4, all of which belongs to the manner of “the materials and the hot airflow enter into the cavity co-currently” as mentioned in this Example. A rotating device is provided at the bottom of the cavity and the rotating device is provided with lifting teeth 4 and driven by the driving shaft 5 of the driving device 1. The rotating device and the driving device are arranged on the rack 2 on which the casing 3 is provided. The rotational speed of the rotating device is 50-500 rpm (being 50 rpm in this Example). The materials are sprayed by the lifting teeth 4 on the rotating device and diffused into the hot air flow. The drying time of the materials in the entire cavity is l-20s (being 12s in this Example). The materials are dried by the hot airflow (mass heat exchange) and then discharged from the drying device. The temperature of the hot air at the air outlet 8 is 120-200 degree Celsius. The hot airflow direction curve 10 is shown in FIG. 2. In this Example, by defining the parameters such as the negative pressure value, the temperature, the oxygen content and the like, the dehydration rate of the drying method defined by the present invention is greatly improved and the explosion threshold value cannot be reached so that no explosion will occur, the workshop will run safely and the drying rate is high. The moisture content of the dried coal is better controlled, and the granularity of the materials is uniform, which effectively guarantees the quality of the dried product. The definition of the present invention makes the drying time of the materials in the entire cavity short, which can ensure a high dehydration rate without causing the pyrolysis (combustion reaction) of the materials, and the materials are dried quickly without sticking to the shell of chamber.

Preferably, the materials are collected through the discharge port 9, a separator of flowing direction of the flue gas and the dust collector. The width of the last chamber is greater than that of the other chambers so that the material flow rate is reduced, and majority of the coal slime is discharged from the discharge port 9.

The drying device of this Example can also be shown in FIG 4, the cavity of the drying device is divided into a plurality of chambers by the baffles, when the materials are disaggregated and sprayed by the lifting teeth and dispersed in the chamber, the disaggregated materials are dried in the chamber (mass heat exchange) with the hot airflow and then flows gradually to the next chamber and are discharged through the discharge port finally. Besides, the drying device of this Example can be shown in FIG. 5, the cavity of the drying device is divided into a plurality of chambers by the staggerly arranged baffles and windshileds, so that the directions of both the hot airflow and the materials in the chambers are S-shaped, the mass and heat exchanges sufficiently and the thermal efficiency is improved.

Table 6. The data of dried non-caking coal in Example 6

Drying rate	600 kgH₂0/m³ h
Increased calorific value	1000 kcal/kg
Dehydration rate	About 60%
Granularity of coal slime	< 6 mm
Processing capacity for single device per hour (wet basis)	60 cubic meter

Example 7

A method for drying weakly caking coal provided in this Example, as shown in FIG. 1- FIG.3, including the following steps: using a gas heating device (commonly, such as a hot air furnace) to generate a hot air flow (flue gas); introducing the hot air flow with a temperature of 200-1500 degree Celsius (being 1000 degree Celsius in this Example) and an oxygen content of less than 10% into the cavity of the drying device from the air inlet 6; the induced draft fan is provided at the end of the air outlet 8 (not shown in figures), making the cavity of the drying device to generate a negative pressure of 100-6000 Pa (being 4000 Pa in this Example), and the flow rate of the hot airflow in the cavity is 8-14 m/s (being 8 m/s in this Example); the setting position of the inlet 7 of the drying device needs to be higher than that of the top of the lifter tooth 4, and it is set on the top of the shell in this Example. Such setting makes the materials and the hot air flow enter into the cavity co-currently. Specifically, the inlet 7 and the air inlet 6 can be set as shown in FIG. 2, and the air inlet 6 and the inlet 7 can also be set on one side of the casing simultaneously, as long as the materials and the hot airflow can be collected before being thrown by the lifting teeth 4, all of which belongs to the manner of “the materials and the hot airflow enter into the cavity co-currently” as mentioned in this Example. A rotating device is provided at the bottom of the cavity and the rotating device is provided with lifting teeth 4 and driven by the driving shaft 5 of the driving device 1. The rotating device and the driving device are arranged on the rack 2 on which the casing 3 is provided. The rotational speed of the rotating device is 50-500 rpm (being 200 rpm in this Example). The materials are sprayed by the lifting teeth 4 on the rotating device and diffused into the hot air flow. The drying time of the materials in the entire cavity is l-5s (being 3s in this Example). The materials are dried by the hot airflow (mass heat exchange) and then discharged from the drying device. The temperature of the hot air at the air outlet 8 is 120-200 degree Celsius. The hot airflow direction curve 10 is shown in FIG. 2. In this Example, by defining the parameters such as the negative pressure value, the temperature, the oxygen content and the like, the dehydration rate of the drying method defined by the present invention is greatly improved and the explosion threshold value cannot be reached so that no explosion will occur, the workshop will run safely and the drying rate is high. The moisture content of the dried coal is better controlled, and the granularity of the materials is uniform, which effectively guarantees the quality of the dried product. The definition of the present invention makes the drying time of the materials in the entire cavity short, which can ensure a high dehydration rate without causing the pyrolysis (combustion reaction) of the materials, and the materials are dried quickly without sticking to the shell of chamber.

Table 7. The data of dried weakly caking coal in Example 7

Drying rate	600 kgH₂0/m³ h
Increased calorific value	1000 kcal/kg
Dehydration rate	About 60%
Granularity of coal slime	< 10 mm
Processing capacity for single device per hour (wet basis)	50 cubic meter

Example 8

A method for drying gas coal provided in this Example, as shown in FIG. 1FIG.3, including the following steps: using a gas heating device (commonly, such as a hot air furnace) to generate a hot air flow (flue gas); introducing the hot air flow with a temperature of 200-1500 degree Celsius (being 900 degree Celsius in this Example) and an oxygen content of less than 10% into the cavity of the drying device from the air inlet 6; the induced draft fan is provided at the end of the air outlet 8 (not shown in figures), making the cavity of the drying device to generate a negative pressure of 100-6000 Pa (being 4000 Pa in this Example), and the flow rate of the hot airflow in the cavity is 8-14 m/s (being 8 m/s in this Example); the setting position of the inlet 7 of the drying device needs to be higher than that of the top of the lifter tooth 4, and it is set on the top of the shell in this Example. Such setting makes the materials and the hot air flow enter into the cavity co-currently. Specifically, the inlet 7 and the air inlet 6 can be set as shown in FIG. 2, and the air inlet 6 and the inlet 7 can also be set on one side of the casing simultaneously, as long as the materials and the hot airflow can be collected before being thrown by the lifting teeth 4, all of which belongs to the manner of “the materials and the hot airflow enter into the cavity co-currently” as mentioned in this Example. A rotating device is provided at the bottom of the cavity and the rotating device is provided with lifting teeth 4 and driven by the driving shaft 5 of the driving device 1. The rotating device and the driving device are arranged on the rack 2 on which the casing 3 is provided. The rotational speed of the rotating device is 50-500 rpm (being 250 rpm in this Example). The materials are sprayed by the lifting teeth 4 on the rotating device and diffused into the hot air flow. The drying time of the materials in the entire cavity is l-5s (being 3s in this Example). The materials are dried by the hot airflow (mass heat exchange) and then discharged from the drying device. The temperature of the hot air at the air outlet 8 is 120-200 degree Celsius. The hot airflow direction curve 10 is shown in FIG. 2. In this Example, by defining the parameters such as the negative pressure value, the temperature, the oxygen content and the like, the dehydration rate of the drying method defined by the present invention is greatly improved and the explosion threshold value cannot be reached so that no explosion will occur, the workshop will run safely and the drying rate is high. The moisture content of the dried coal is better controlled, and the granularity of the materials is uniform, which effectively guarantees the quality of the dried product. The definition of the present invention makes the drying time of the materials in the entire cavity short, which can ensure a high dehydration rate without causing the pyrolysis (combustion reaction) of the materials, and the materials are dried quickly without sticking to the shell of chamber.

Table 8. The data of dried gas coal in Example 8

Drying rate	600 kgH₂0/m³h
Increased calorific value	900 kcal/kg
Dehydration rate	About 50%
Granularity of coal slime	< 10 mm
Processing capacity for single device per hour (wet basis)	50 cubic meter

Example 9

A method for drying lean coal provided in this Example, as shown in FIG.

1- FIG.3, including the following steps: using a gas heating device (commonly, such as a hot air furnace) to generate a hot air flow (flue gas); introducing the hot air flow with a temperature of 200-1500 degree Celsius (being 1000 degree Celsius in this Example) and an oxygen content of less than 10% into the cavity of the drying device from the air inlet 6; the induced draft fan is provided at the end of the air outlet 8 (not shown in figures), making the cavity of the drying device to generate a negative pressure of 100-6000 Pa (being 4000 Pa in this Example), and the flow rate of the hot airflow in the cavity is 8-14 m/s (being 8 m/s in this Example); the setting position of the inlet 7 of the drying device needs to be higher than that of the top of the lifter tooth 4, and it is set on the top of the shell in this Example. Such setting makes the materials and the hot air flow enter into the cavity co-currently. Specifically, the inlet 7 and the air inlet 6 can be set as shown in FIG. 2, and the air inlet 6 and the inlet 7 can also be set on one side of the casing simultaneously, as long as the materials and the hot airflow can be collected before being thrown by the lifting teeth 4, all of which belongs to the manner of “the materials and the hot airflow enter into the cavity co-currently” as mentioned in this Example. A rotating device is provided at the bottom of the cavity and the rotating device is provided with lifting teeth 4 and driven by the driving shaft 5 of the driving device 1. The rotating device and the driving device are arranged on the rack 2 on which the casing 3 is provided. The rotational speed of the rotating device is 50-500 rpm (being 180 rpm in this Example). The materials are sprayed by the lifting teeth 4 on the rotating device and diffused into the hot air flow. The drying time of the materials in the entire cavity is l-5s (being 3s in this Example). The materials are dried by the hot airflow (mass heat exchange) and then discharged from the drying device. The temperature of the hot air at the air outlet 8 is 120-200 degree Celsius. The hot airflow direction curve 10 is shown in FIG. 2. In this Example, by defining the parameters such as the negative pressure value, the temperature, the oxygen content and the like, the dehydration rate of the drying method defined by the present invention is greatly improved and the explosion threshold value cannot be reached so that no explosion will occur, the workshop will run safely and the drying rate is high. The moisture content of the dried coal is better controlled, and the granularity of the materials is uniform, which effectively guarantees the quality of the dried product. The definition of the present invention makes the drying time of the materials in the entire cavity short, which can ensure a high dehydration rate without causing the pyrolysis (combustion reaction) of the materials, and the materials are dried quickly without sticking to the shell of chamber.

Table 9. The data of dried lean coal in Example 9

Drying rate

600 kgH₂0/m³h

Increased calorific value	900 kcal/kg
Dehydration rate	About 60%
Granularity of coal slime	< 10 mm
Processing capacity for single device per hour (wet basis)	50 cubic meter

Example 10

A method for drying anthracite provided in this Example, as shown in FIG. 1- FIG3, including the following steps: using a gas heating device (commonly, such as a hot air furnace) to generate a hot air flow (flue gas); introducing the hot air flow with a temperature of 200-1500 degree Celsius (being 1000 degree Celsius in this Example) and an oxygen content of less than 10% into the cavity of the drying device from the air inlet 6; the induced draft fan is provided at the end of the air outlet 8 (not shown in figures), making the cavity of the drying device to generate a negative pressure of 100-6000 Pa (being 4000 Pa in this Example), and the flow rate of the hot airflow in the cavity is 8-14 m/s (being 8 m/s in this Example); the setting position of the inlet 7 of the drying device needs to be higher than that of the top of the lifter tooth 4, and it is set on the top of the shell in this Example. Such setting makes the materials and the hot air flow enter into the cavity co-currently. Specifically, the inlet 7 and the air inlet 6 can be set as shown in FIG 2, and the air inlet 6 and the inlet 7 can also be set on one side of the casing simultaneously, as long as the materials and the hot airflow can be collected before being thrown by the lifting teeth 4, all of which belongs to the manner of “the materials and the hot airflow enter into the cavity co-currently” as mentioned in this Example. A rotating device is provided at the bottom of the cavity and the rotating device is provided with lifting teeth 4 and driven by the driving shaft 5 of the driving device 1. The rotating device and the driving device are arranged on the rack 2 on which the casing 3 is provided. The rotational speed of the rotating device is 50-500 rpm (being 200 rpm in this Example). The materials are sprayed by the lifting teeth 4 on the rotating device and diffused into the hot air flow. The drying time of the materials in the entire cavity is I-5 s (being 3s in this Example). The materials are dried by the hot airflow (mass heat exchange) and then discharged from the drying device. The temperature of the hot air at the air outlet 8 is 120-200 degree Celsius. The hot airflow direction curve 10 is shown in FIG. 2. In this Example, by defining the parameters such as the negative pressure value, the temperature, the oxygen content and the like, the dehydration rate of the drying method defined by the present invention is greatly improved and the explosion threshold value cannot be reached so that no explosion will occur, the workshop will run safely and the drying rate is high. The moisture content of the dried coal is better controlled, and the granularity of the materials is uniform, which effectively guarantees the quality of the dried product. The definition of the present invention makes the drying time of the materials in the entire cavity short, which can ensure a high dehydration rate without causing the pyrolysis (combustion reaction) of the materials, and the materials are dried quickly without sticking to the shell of chamber.

Table 10. The data of dried anthracite in Example 10

Drying rate	600 kgH₂0/m³ h
Increased calorific value	1000 kcal/kg
Dehydration rate	About 70%
Granularity of coal slime	< 10 mm
Processing capacity for single device per hour (wet basis)	60 cubic meter

Example 11

A method for drying minicipal sludge provided in this Example, as shown in FIG. 1- FIG.3, including the following steps: using a gas heating device (commonly, such as a hot air furnace) to generate a hot air flow (flue gas); introducing the hot air flow with a temperature of 200-1500 degree Celsius (being 1000 degree Celsius in this Example) and an oxygen content of less than 10% into the cavity of the drying device from the air inlet 6; the induced draft fan is provided at the end of the air outlet 8 (not shown in figures), making the cavity of the drying device to generate a negative pressure of 100-6000 Pa (being 4000 Pa in this Example), and the flow rate of the hot airflow in the cavity is 8-14 m/s (being 8 m/s in this Example); the setting position of the inlet 7 of the drying device needs to be higher than that of the top of the lifter tooth 4, and it is set on the top of the shell in this Example. Such setting makes the materials and the hot air flow enter into the cavity co-currently. Specifically, the inlet 7 and the air inlet 6 can be set as shown in FIG. 2, and the air inlet 6 and the inlet 7 can also be set on one side of the casing simultaneously, as long as the materials and the hot airflow can be collected before being thrown by the lifting teeth 4, all of which belongs to the manner of “the materials and the hot airflow enter into the cavity co-currently” as mentioned in this Example. A rotating device is provided at the bottom of the cavity and the rotating device is provided with lifting teeth 4 and driven by the driving shaft 5 of the driving device 1. The rotating device and the driving device are arranged on the rack 2 on which the casing 3 is provided. The rotational speed of the rotating device is 50-500 rpm (being 200 rpm in this Example). The materials are sprayed by the lifting teeth 4 on the rotating device and diffused into the hot air flow. The drying time of the materials in the entire cavity is l-5s (being 3s in this Example). The materials are dried by the hot airflow (mass heat exchange) and then discharged from the drying device. The temperature of the hot air at the air outlet 8 is 120-200 degree Celsius. The hot airflow direction curve 10 is shown in FIG. 2. In this Example, by defining the parameters such as the negative pressure value, the temperature, the oxygen content and the like, the dehydration rate of the drying method defined by the present invention is greatly improved and the explosion threshold value cannot be reached so that no explosion will occur, the workshop will run safely and the drying rate is high. The moisture content of the dried coal is better controlled, and the granularity of the materials is uniform, which effectively guarantees the quality of the dried product. The definition of the present invention makes the drying time of the materials in the entire cavity short, which can ensure a high dehydration rate without causing the pyrolysis (combustion reaction) of the materials, and the materials are dried quickly without sticking to the shell of chamber.

Table 11. The data of dried minicipal sludge in Example 11

Drying rate	600 kgH₂0/m³ h
Dehydration rate	About 80%
Granularity of coal slime	< 10 mm
Processing capacity for single device per hour (wet basis)	30 cubic meter

Example 12

A method for drying nonferrous metal tailings provided in this Example, as shown in FIG. 1- FIG3, including the following steps: using a gas heating device (commonly, such as a hot air furnace) to generate a hot air flow (flue gas); introducing the hot air flow with a temperature of 200-1500 degree Celsius, preferably, 700-1500 degree Celsius (being 1100 degree Celsius in this Example) and an oxygen content of less than 10% into the cavity of the drying device from the air inlet 6; the induced draft fan is provided at the end of the air outlet 8 (not shown in figures), making the cavity of the drying device to generate a negative pressure of 100-6000 Pa (being 4000 Pa in this Example), and the flow rate of the hot airflow in the cavity is 8-14 m/s (being 8 m/s in this Example); the setting position of the inlet 7 of the drying device needs to be higher than that of the top of the lifter tooth 4, and it is set on the top of the shell in this Example. Such setting makes the materials and the hot air flow enter into the cavity co-currently. Specifically, the inlet 7 and the air inlet 6 can be set as shown in FIG. 2, and the air inlet 6 and the inlet 7 can also be set on one side of the casing simultaneously, as long as the materials and the hot airflow can be collected before being thrown by the lifting teeth 4, all of which belongs to the manner of “the materials and the hot airflow enter into the cavity co-currently” as mentioned in this Example. A rotating device is provided at the bottom of the cavity and the rotating device is provided with lifting teeth 4 and driven by the driving shaft 5 of the driving device 1. The rotating device and the driving device are arranged on the rack 2 on which the casing 3 is provided. The rotational speed of the rotating device is 50-500 rpm (being 200 rpm in this Example). The materials are sprayed by the lifting teeth 4 on the rotating device and diffused into the hot air flow. The drying time of the materials in the entire cavity is l-5s (being 3s in this Example). The materials are dried by the hot airflow (mass heat exchange) and then discharged from the drying device. The temperature of the hot air at the air outlet 8 is 120-200 degree Celsius. The hot airflow direction curve 10 is shown in FIG. 2. In this Example, by defining the parameters such as the negative pressure value, the temperature, the oxygen content and the like, the dehydration rate of the drying method defined by the present invention is greatly improved and the explosion threshold value cannot be reached so that no explosion will occur, the workshop will run safely and the drying rate is high. The moisture content of the dried coal is better controlled, and the granularity of the materials is uniform, which effectively guarantees the quality of the dried product. The definition of the present invention makes the drying time of the materials in the entire cavity short, which can ensure a high dehydration rate without causing the pyrolysis (combustion reaction) of the materials, and the materials are dried quickly without sticking to the shell of chamber.

Table 12. The data of dried nonferrous metal tailings in Example 12

Drying rate	600 kgH₂0/m³h
Dehydration rate	About 80%
Granularity of coal slime	< 6 mm
Processing capacity for single device per hour (wet basis)	30 cubic meter

io Examples 13-28

The following Examples only list the differences from the above Examples (taking Example 1 for an example). For the simplicity of the patent text, only different parameters are listed in a table. Combining the above Examples (taking Example 1 for an example) and the contents disclosed below, those skilled in the 15 art can fully realize the technical solutions of these Examples. The differences are as follows: Those skilled in the art can fully achieve the technical solutions of the Examplesby taking Example 1 as an example and the contents disclosed below. The differences are as follows:

Table 13. The parameters defined in Example 13-28

Embodi- ments

Objects being dried

Temperatures of hot airflow / Degree Celsius

Oxygen content

Negative pressure /Pa

Flow rate of hot airflow/) m/s)

Rotation speed of rotating device /rpm

Drying time/s

Example 13	Coal slime	200	12%	6000	2	500	20
Example 14	Coal slime	1500	6%	100	24	50	1
Example 15	Coal slime	500	10%	1000	8	400	8
Example 16	Coal slime	1100	9%	300	14	150	3
Example 17	Low rank coal	200	12%	6000	2	500	20
Example 18	Low rank coal	1500	7%	100	24	50	1
Example 19	Low rank coal	600	10%	1000	8	400	8
Example 20	Low rank coal	1300	9%	250	16	150	4
Example 21	Municipal sludge	200	12%	6000	2	500	20
Example 22	Municipal sludge	1500	7%	100	24	50	1
Example 23	Municipal sludge	1000	10%	3000	9	300	8
Example 24	Municipal sludge	1200	5%	800	16	200	5
Example 25	Nonferrous metal tailings	200	12%	6000	2	500	20
Example 26	Nonferrous metal tailings	1500	7%	100	24	50	1

Example 27	Nonferrous metal tailings	700	10%	3000	9	400	10
Example 28	Nonferrous metal tailings	1000	4%	800	16	200	6

The low rank coal is any one of lignite, long flame coal, non-caking coal, weakly caking coal, blast furnace injection coal, gas coal, gas fat coal, meager lean coal, lean coal, fat coal and anthracite. After the test, the drying effect of the above Examples is also excellent and will not be described in detail herein.

It should be noted that the above Examples are only intended to illustrate the technical solutions of the present invention rather than the limitation to the protection scope of the present invention. Although the present invention is described in detail with reference to the preferred Examples, those skilled in the art should understand that the technical solutions of the present invention may 10 be modified or equivalently substituted without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for drying materials, characterized in that: comprising the following steps:

introducing the hot airflow with temperature of 200-1500 degrees Celsius and oxygen content less than 12% into the cavity of a drying device from an air inlet, generating negative pressure of 100-6000 Pa in the cavity of the drying device with 2-24 m/s flow rate of the hot airflow in the cavity by an induced draft fan provided at the tail end of an air outlet;

the materials and the hot airflow entering into the cavity concurrently, the materials crushed by the lifting teeth being sprayed and diffused into the hot airflow, the drying time of the materials in the entire cavity is 1-20 s, rotating devices are provided at the bottom of the cavity, the setting position of the inlet of the drying device is higher than that of the top of the lifting teeth on the rotating devices, the rotational speed of the rotating devices is 50-500 rpm; and the materials being dried by the hot airflow and then discharged from the drying device.

2. The method for drying materials according to claim 1, characterized in that: the cavity of the drying device is divided into a plurality of chambers by baffles, after being dried in the chambers with the hot airflow, the materials flow gradually to the next chamber and are finally discharged through the discharge port.

3. The method for drying materials according to claim 1, characterized in that: the cavity of the drying device is divided into a plurality of chambers by the baffles and windshields being staggerly arranged, so that the flow directions of both the hot air flow and the materials in the chamber are S-shaped.

4. The method of drying materials according to claim 3, characterized in that: the width of the last chamber is greater than that of the other chambers, so that the flow rate of the materials is reduced.

5. The method for drying materials according to claim 4, characterized in that: the materials are collected through a discharge port, a separator of flowing direction of the flue gas and a dust collector.

6. The method of drying materials according to any one of claims 1-5, characterized in that: the temperature at the air outlet of the hot airflow is 60-200 degrees Celsius.

7. The method for drying materials according to any one of claims 1-6, characterized in that: the granularity of the materials after drying is 0.01-15 mm.

8. The method for drying materials according to any one of claims 1-5, characterized in that: the hot airflow at the air inlet has a temperature of 800-1100 degrees Celsius and an oxygen content of less than 8%, the negative pressure of the drying device is 900- 6000Pa, the flow rate of the hot airflow in the cavity is 8-18m/s; the rotational speed of the rotating devices is 100-400 rpm, and the drying time of the materials in the entire cavity is 1-5 s.

9. The method for drying materials according to any one of claims 1-5, characterized in that: the hot airflow at the air inlet has a temperature of 600-900 degrees Celsius and an oxygen content of less than 11%, the negative pressure of the drying device is 900-6000 Pa, the flow rate of the hot airflow in the cavity is 8-14 m/s; the rotational speed of the rotating devices is 100-400 rpm, and the drying time of the materials in the entire cavity is 1-5 s.

10. The method for drying materials according to any one of claims 1-5, characterized in that: the drying method is used for drying lignite, long flame coal, non-caking coal, weakly caking coal, blast furnace injection coal, gas coal, gas fat coal, meager lean coal, lean coal, fat coal, anthracite, coal slime, municipal sludge or non-ferrous metal tailings.