CN112551925B

CN112551925B - Device and method for comprehensively utilizing gypsum raw material

Info

Publication number: CN112551925B
Application number: CN202011182945.1A
Authority: CN
Inventors: 张美菊; 朱庆山
Original assignee: Zhongke Nanjing Green Manufacturing Industry Innovation Research Institute; Institute of Process Engineering of CAS
Current assignee: Zhongke Nanjing Green Manufacturing Industry Innovation Research Institute; Institute of Process Engineering of CAS
Priority date: 2020-10-29
Filing date: 2020-10-29
Publication date: 2022-08-05
Anticipated expiration: 2040-10-29
Also published as: CN112551925A

Abstract

The invention provides a device and a method for comprehensively utilizing gypsum raw materials. The method utilizes a fluidized roasting method to continuously roast materials, can maintain a uniform temperature field, and can realize the recycling of waste heat. The method is beneficial to treating the gypsum raw material under the condition of continuous and large treatment capacity, the system has high heat efficiency, stable product quality and flexible adjustment of the roasting process; has wide application prospect.

Description

Device and method for comprehensively utilizing gypsum raw material

Technical Field

The invention relates to the technical field of gypsum treatment, in particular to a device and a method for comprehensively utilizing gypsum raw materials.

Background

The main methods for processing the gypsum raw material into the semi-hydrated gypsum include a calcination method and a high-temperature flash-burning method. The calcining method is the main method for producing the semi-hydrated gypsum at present, and the method does not need water washing, thereby avoiding the waste of water resources and secondary pollution.

RU2005119689A, PL2013000019W, EP15752713.6, US15119688, RU2007101877A, GB2028783A all disclose techniques of adding phosphogypsum with different additives and ash, firing cement clinker in a rotary furnace.

GB2605072A discloses a method for preparing semi-hydrated gypsum by roasting in a rotary kiln at the temperature of 200-240 ℃; the phosphogypsum is calcined by an international patent PCT/CN2017/112084 applied by Zhengzhou Sandi building science and technology Limited company to obtain the hemihydrate gypsum by adopting a preheating roller, a calcining roller, a reducing roller and the like.

GB2028783A discloses a process for the preparation of gypsum by subjecting phosphogypsum to a two-stage heat treatment with the addition of lime, the first stage being the dehydration at a temperature of 110 to 150 degrees celsius for 30 to 90 minutes and the second stage being the conditioning at 130 to 180 degrees celsius for 10 minutes to several hours to produce gypsum.

Therefore, the semi-hydrated gypsum prepared by the prior art mainly adopts a rotary kiln, a rotary furnace, a fluidized bed furnace and the like, the calcination time is long, the occupied area of equipment is large, and the energy consumption for operation is high.

CN1594175A discloses a construction process of internal heating building gypsum, which adopts a fluidized bed furnace to provide a heat source, adopts an internal heating rotary kiln with a lifting plate in a calcining system, lifts materials by the lifting plate to enhance heat transfer, and improves the thermal efficiency of phosphogypsum calcining, wherein the thermal efficiency can reach 49-61%.

CN104310830A discloses a method for producing beta-high purity gypsum powder by using phosphogypsum, which adopts an FC compartment calciner to indirectly exchange heat in a heat exchange tube by hot flue gas. The heat utilization rate is low.

CN207468502U discloses a suspended air flow type phosphogypsum integrated treatment device, and CN107651870A discloses a suspended air flow type phosphogypsum integrated treatment device and method, which comprise a drying unit, a high-temperature impurity removal unit, a calcining unit and a cooling unit. The ardealite is dried by hot wind with the gas speed of 15-25m/s and the temperature of 400-800 ℃, enters an impurity removal furnace to remove impurities under the action of the hot wind with the temperature of 450-800 ℃, and is calcined firstly under the condition of the hot wind with the temperature of 110-220 ℃. In the process, a plurality of high-temperature flue gases interact with the phosphogypsum, and the excessive dehydration is easy to generate anhydrite to cause overburning. The impurity removing furnace and the phase change furnace are of an inner cylinder structure and an outer cylinder structure, and the reaction time of materials and gas in the furnace is not easy to control.

CN107902932A discloses a phosphogypsum calcining device, which consists of 2 preheating rollers, 2 calcining rollers and reduction rollers, wherein conveying devices are adopted among the rollers for conveying. The calcination tail gas and the materials are indirectly contacted with the drying materials in the preheating roller for preheating, so that the defect that the calcination tail gas has high water content and can influence the free water removal of the materials is effectively avoided. However, the maximum diameter of the roller is 3.3 meters, and the roller needs larger power for running, so that the construction cost is lower, but the running cost is higher. In addition, the solid materials are deposited at the bottom of the roller by gravity, although the roller can not improve the uniformity of the reaction process even though the roller rotates.

CN110092599A discloses a phosphogypsum calcining system, which comprises a calcining furnace, a flaming furnace, a settling chamber, a front dust remover, a preheating furnace, a rear dust remover and a reducing furnace-induced draft fan. Wherein the preheating furnace is a core-through tube type rotary kiln, the calcining furnace is a double-cylinder rotary calcining furnace, and the whole furnace body rotates to pretreat materials during operation. The flame-throwing furnace is arranged at one end of the feed inlet of the calcining furnace, the flame-throwing direction faces the open end of the inner cylinder of the calcining furnace, the high-temperature flue gas is easily in contact with the materials to generate an overburning phenomenon, the rotary kiln has high running power consumption, and the occupied area is large.

CN110143773A discloses a phosphogypsum calcining system, which comprises a calcining furnace, a flaming furnace, a rear dust remover, a front dust remover, a preheating furnace, a reducing furnace, a settling chamber and an induced draft fan. The calcining equipment is reasonably arranged, the structure is compact, the waste heat is reasonably utilized, and the hot air circulation structure is simplified. The technology adopts a double-cylinder rotary calcining furnace.

CN201614351U discloses an integrated device for waste heat utilization of a phosphogypsum modified fluidized bed furnace, which comprises a fluidized bed furnace, a rotary kiln, a cloth bag dust removal device, waste heat recycling and the like. The coal of the device is burnt in a fluidized bed furnace, and the smoke enters a rotary kiln to modify and calcine the phosphogypsum. The device increases the impurity content by the coal combustion flue gas entering the rotary kiln flue gas dust directly entering the phosphogypsum.

CN203878066U discloses FC furnace dry calcination system. The system comprises a coal-fired fluidized bed furnace, wherein flue gas generated by the coal-fired fluidized bed furnace enters an FC calcining furnace, and the flue gas is in indirect contact with gypsum through a metal transmission heat pipe, so that the condition that fly ash is mixed and enters finished gypsum powder when a heat source is in direct contact with the gypsum is avoided. The air of the blower enters the FC calcining furnace to blow the raw gypsum to enhance the heat exchange effect, but the indirect heat exchange efficiency is lower than that of direct contact heat exchange.

CN208414262U discloses a novel phosphogypsum calcining device, which adopts an internal heat pipe type rotary kiln, and flue gas is introduced into the internal heat pipe to be indirectly contacted with phosphogypsum, so that the flue gas does not pollute the raw materials while heat transfer is ensured. The equipment still adopts the rotary kiln, and because the heat pipe is arranged in the center of the rotary kiln and the material is deposited at the bottom of the rotary kiln, insufficient heat exchange is caused, so that the phosphogypsum is not uniformly roasted.

CN208346051U discloses a system for preparing building gesso by adopting phosphogypsum, which comprises a loader, a drier, a calcining machine, a bucket elevator, heat source equipment and a waste gas treatment device. The drying machine is a two-cylinder rotary drying machine, and the drying temperature is 400-500 ℃ for 20 m. The calcining machine is a three-cylinder calcining machine at 170 ℃. The system filters the flue gas by using ceramic dust removal equipment and then uses the flue gas in the roasting process, so that the content of the fly ash mixed in the building gypsum is reduced. The large-scale rotary equipment is adopted as the main drying and roasting equipment, the occupied area is large, the large-scale rotary equipment is not easy to be used in the processing process with large treatment capacity, and the operation cost is high.

CN108658484A discloses a sectional treatment process for building gypsum, which comprises drying phosphogypsum in a hot air type drying furnace at 390-410 ℃ for 15s, heating the phosphogypsum to 100 ℃ by adopting a tunnel furnace, and heating the phosphogypsum in a rotary heating furnace at 190-200 ℃ for 20-30 min. The building gypsum is obtained by ball milling the materials. The process adopts a tunnel kiln and a rotary heating furnace, so that the occupied area is large, and the operation and maintenance cost of the equipment is high.

CN207175793U discloses a device for preparing building gypsum from phosphogypsum, which is characterized in that the phosphogypsum and lime are treated in a retting warehouse and then enter a rotary calcining kiln for calcining, and then the materials are cooled and ground to obtain the building gypsum. The heat source of the device is hot air generated by a fluidized bed furnace and phosphogypsum is calcined in a rotary calcining kiln.

CN204417351U discloses a phosphogypsum calcining system with a flash dryer, which adopts the flash dryer and a rotary kiln to dry and calcine materials, and the process optimizes the utilization of hot gas. Flue gas generated by the combustion chamber enters the rotary kiln to directly contact with the phosphogypsum.

CN204417348U discloses a phosphogypsum calcining system with crushing and drying functions, which adopts a cyclone preheater to dry phosphogypsum and then enters a rotary kiln for calcination. The system can better realize heat exchange and mixing of materials, improve the heat efficiency and stabilize the material components of the rotary kiln.

In summary, in the prior art, the calcination is mainly performed by directly exchanging heat between the rotary kiln and hot gas or indirectly exchanging heat between the rotary kiln and the hot gas through the heat exchange tubes, the material is heated unevenly, the quality of the product obtained by insufficient calcination is poor, the rotary power consumption of the rotary kiln is large, and the occupied area is large. Some calcining furnaces with separated chambers and heat exchange tubes are adopted for calcining, the calcining time is longer, and the utilization rate of indirect heat exchange heat is lower. Resulting in low single line yield, high energy consumption and serious dust pollution. The produced semi-hydrated gypsum has unstable quality and can not meet the requirements of downstream gypsum cementing material product industries such as gypsum plasterboard, gypsum lath, fiber reinforced gypsum board, gypsum block or gypsum mortar and the like.

Therefore, a new set of equipment and method for preparing hemihydrate gypsum needs to be developed.

Disclosure of Invention

In view of the problems in the prior art, the invention provides a device and a method for comprehensively utilizing gypsum raw materials, the device and the method have the advantages of uniform roasting process, stable product quality and no overburning phenomenon; the waste heat in the process can be reasonably recycled, and the heat utilization rate is improved; the roasting temperature is flexibly adjusted; can effectively and comprehensively utilize the industrial byproduct gypsum to prepare the calcined gypsum, and achieves the aim of resource utilization of solid waste.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the invention provides a device for comprehensively utilizing gypsum raw materials, which comprises a pretreatment unit, a preheating unit, a fluidized roasting unit and a finished product unit which are sequentially connected; the device also comprises a dust removal unit connected with the fluidization roasting unit.

According to the device for comprehensively utilizing the gypsum raw material, the fluidized roasting unit can provide a stable temperature field, the material is in contact with the gas phase in a fluidized form, the overburning phenomenon can be effectively prevented, and the roasting temperature can be flexibly adjusted; and the gas generated by the fluidized roasting unit is discharged in a tail gas form after being dedusted by the dedusting unit, so that the problem of dust pollution is effectively alleviated, and the prepared semi-hydrated gypsum and gypsum finished products have stable quality.

Preferably, the pretreatment unit comprises a feed inlet.

Preferably, the pre-treatment unit comprises a conditioning agent inlet.

Preferably, the pre-treatment unit includes an impurity discharge port.

Preferably, the fluidized roasting unit comprises a first gas outlet.

Preferably, the first gas outlet is connected to a preheating unit.

When the device comprises the preheating unit, the first gas outlet is preferably connected with the preheating unit, and the material is preheated by using the gas waste heat after fluidized roasting, so that the heat utilization rate is improved.

Preferably, the fluidized roasting unit comprises a conditioning medium inlet.

Preferably, the fluidising calcination unit comprises an air inlet and a fuel inlet.

When the device does not comprise a heat supply unit, the fluidized roasting device adopted in the fluidized roasting unit can be provided with a combustion chamber, and the combustion chamber is provided with an air inlet and a fuel inlet, so that the process flow is shorter, and the occupied space is saved.

Preferably, the dust removal unit comprises a solids outlet.

Preferably, the solids outlet is connected to the fluidisation roasting unit.

Preferably, the dust removal unit comprises an off-gas outlet.

Preferably, the finished product unit comprises an additive inlet and a finished product outlet.

Preferably, the apparatus further comprises a preheating unit disposed between the pretreatment unit and the fluidized roasting unit.

When the gypsum raw material is selected from fibrous gypsum ore, layered gypsum ore or waste gypsum mould, the pretreatment unit is not needed.

Preferably, the device for comprehensively utilizing the gypsum raw materials further comprises a heat supply unit connected with the fluidized roasting unit.

Preferably, the heat supply unit is further connected with the preheating unit.

The hot gas conveying of the heat supply unit and the preheating unit can be mixed with the gas generated by the fluidized roasting unit and then sent into the preheating unit, and can also be respectively sent into the preheating unit.

Preferably, the preheating unit comprises a second gas outlet.

Preferably, the second gas outlet is connected to the dust removal unit.

Preferably, the heat supply unit comprises an air inlet and a fuel inlet.

Preferably, the pre-treatment unit comprises a crushing device.

Preferably, the crushing device comprises any one of a squirrel cage crusher, a hammer crusher, a claw crusher, a jaw crusher, an impact crusher, a cone crusher, a raymond mill or a ball mill.

Preferably, the pretreatment unit further comprises a neutralization device.

The neutralization device can adjust the pH value of the gypsum raw material, and is beneficial to the subsequent preparation of the semi-hydrated gypsum.

Preferably, the fluidized roasting unit comprises a fluidized roasting apparatus.

Preferably, the fluidized roasting apparatus comprises any one of a riser, a bubbling fluidized bed, a stirred fluidized bed or a vibrated fluidized bed or a combination of at least two of them.

Preferably, the preheating unit comprises a 1-3 stage cyclone preheater and/or a fluidized bed preheater.

The connection of the specific device in each unit is not particularly limited, any device which can be used for realizing each function and is well known to the technical personnel in the field can be adopted, and the key point of the invention is that the whole process device can realize the preparation of the semi-hydrated gypsum, the product quality is stable, and the dust pollution is small.

In a second aspect, the invention provides a method for comprehensively utilizing gypsum raw materials, which comprises the following steps:

(1) pretreating a gypsum raw material to obtain a pretreated material;

(2) the pretreatment material is subjected to fluidized roasting, gas after the fluidized roasting is discharged after heat recovery and dust removal, and a solid phase after the fluidized roasting is roasted gypsum;

(3) and (3) blending the calcined gypsum in the step (2) with an additive to obtain a gypsum finished product.

The method for comprehensively utilizing the gypsum raw material provided by the invention roasts the pretreated material in a fluidized roasting mode, can maintain a uniform temperature field, humidity and a better material fluidization state required by reaction, increases the regulation and control flexibility of the roasting process, and stabilizes the product quality.

Preferably, the gypsum raw material in step (1) includes any one or a combination of at least two of phosphogypsum, desulfurized gypsum, gypsum mine waste, citric acid gypsum, fluorgypsum, salt gypsum, gourmet powder gypsum, copper gypsum, titanium gypsum, boron gypsum, waste gypsum material, fibrous gypsum mine, laminar gypsum mine or waste gypsum mold, wherein typical non-limiting combinations are a combination of fluorgypsum and gourmet powder gypsum, a combination of fluorgypsum and fibrous gypsum mine, a combination of fluorgypsum and copper gypsum, a combination of gourmet powder gypsum and fibrous gypsum mine, a combination of fibrous gypsum mine and phosphogypsum, a combination of fibrous gypsum mine and copper gypsum, a combination of copper gypsum and phosphogypsum, a combination of phosphogypsum and salt gypsum, and the like.

The gypsum raw materials preferably adopt industrial byproduct gypsum, namely the invention preferably provides a comprehensive utilization device and a method of the industrial byproduct gypsum, wherein the industrial byproduct gypsum comprises phosphogypsum, desulfurized gypsum, citric acid gypsum, fluorgypsum, salt gypsum, monosodium glutamate gypsum, copper gypsum, titanium gypsum, boron gypsum and the like, and the industrial byproduct gypsum can be fully utilized to reduce environmental pollution and can be prepared into high-stability hemihydrate gypsum and gypsum finished products.

The gypsum raw material can also adopt conventional gypsum ore as the raw material, and can also prepare semi-hydrated gypsum and gypsum finished products with excellent performance.

Preferably, the pre-treatment comprises: the gypsum raw material is subjected to any one or the combination of at least two of crushing, screening and impurity removal or pH adjustment to obtain a pretreatment material.

The pretreatment of the invention has different pretreatment modes according to different raw materials, and specifically, the pretreatment can be only crushing treatment, or the combination of crushing and screening impurity removal, or the combination of crushing, screening impurity removal and pH adjustment, or the combination of crushing and pH adjustment, and the like.

When the gypsum raw material is a large material, the large gypsum raw material is converted into a small material through crushing; and screening and impurity removing steps can be added to remove large metal, woven bags and other impurities.

Preferably, the pH adjustment comprises: mixing the gypsum raw material with a regulator to obtain a pretreatment material.

Preferably, the conditioning agent comprises an alkaline substance.

Preferably, the alkaline substance comprises quicklime and/or slaked lime.

Preferably, the modifier accounts for 0.5-5 wt% of the mass of the screened and impurity-removed gypsum raw material, and may be, for example, 0.5 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, 2 wt%, 2.2 wt%, 2.5 wt%, 2.8 wt%, 3 wt%, 3.2 wt%, 3.5 wt%, 3.8 wt%, 4 wt%, 4.5 wt%, or 5 wt%, and preferably 0.5-3 wt%.

Preferably, the pH value after pH adjustment is 4 to 7, for example, 4, 4.2, 4.5, 4.8, 5, 5.2, 5.5, 5.8, 6, 6.2, 6.5, 6.8 or 7, and preferably 4.5 to 6.5.

Preferably, the pretreated material in the step (2) is preheated and then fluidized and roasted.

Preferably, the preheating comprises: the pretreatment feed is preheated to a first temperature.

The heat for preheating comes from the gas of the heat supply unit and the fluidizing roasting unit, and the hot gas and the solid material containing water exchange heat rapidly to remove part of the attached water in the preheating process.

Preferably, the preheating process is heated by hot gas and/or gas generated by the fluidized roasting in step (2).

Preferably, the first temperature is 60 to 110 ℃, for example, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃, 95 ℃, 100 ℃, 105 ℃ or 110 ℃ and the like.

Preferably, the preheated pretreatment feed has a water content of < 10 wt%, and may be, for example, 9.9 wt%, 9.8 wt%, 9.5 wt%, 9.0 wt%, 8.9 wt%, 8.5 wt%, 8 wt%, 7 wt%, 6.5 wt%, or the like.

Preferably, the gas generated by preheating is discharged after dedusting.

Preferably, the fluidized roasting in step (2) comprises: and (2) carrying out chemical reaction on the pretreated material in the step (1) under the action of hot gas, and removing part of crystal water to obtain the calcined gypsum.

Preferably, the hot gas comprises any one of or a combination of at least two of post-dust extraction flue gas, air, nitrogen or water vapor, with typical non-limiting combinations being flue gas/nitrogen, air/flue gas or air/nitrogen.

Preferably, the temperature of the hot gas is 120 to 950 ℃, for example, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 200 ℃, 250 ℃, 300 ℃, 350 ℃, 400 ℃, 450 ℃, 500 ℃, 550 ℃, 600 ℃, 700 ℃, 800 ℃, 900 ℃ or 950 ℃.

Preferably, the fluidized roasting temperature is 120 to 550 ℃, for example, 120 ℃, 150 ℃, 200 ℃, 250 ℃, 300 ℃, 350 ℃, 400 ℃, 450 ℃, 500 ℃ or 550 ℃, preferably 135 to 450 ℃.

Preferably, the fluidized roasting time is 5-180 min, for example, 5min, 10min, 20min, 50min, 80min, 100min, 110min, 120min, 140min, 150min, 160min or 180min, and the like, and preferably 20-150 min.

Preferably, the gas velocity during the fluidized roasting is 0.01-10 m/s, such as 0.01m/s, 1m/s, 1.2m/s, 1.5m/s, 2m/s, 2.5m/s, 3m/s, 3.5m/s, 4m/s, 4.5m/s, 5m/s, 5.5m/s, 6m/s, 6.5m/s, 7m/s, 7.5m/s, 8m/s, 9m/s, or 10m/s, preferably 0.05-7 m/s.

Preferably, a regulating medium is added in the fluidized roasting process.

The regulating medium can regulate the atmosphere and temperature in the roasting process in time, the temperature field is uniform, and the product quality is stable.

Preferably, the conditioning medium comprises any one of air, water vapor, water or nitrogen or a combination of at least two of them, with typical non-limiting combinations being air/water vapor, water/nitrogen or air/nitrogen, and the like.

Preferably, the finished product processing in step (3) comprises: and (3) mixing the calcined gypsum obtained in the step (2) with an additive to obtain a gypsum finished product.

Preferably, the gypsum finished product comprises any one of terrace gypsum rapid-wall gypsum, plastering gypsum, gypsum blocks, cement retarder or light plastering mortar and the like.

As a preferable technical scheme of the invention, the method comprises the following steps:

(1) crushing, screening, removing impurities and adjusting pH of a gypsum raw material to obtain a pretreatment material; the pH adjustment comprises: mixing the gypsum raw material after screening and impurity removal with an alkaline substance to obtain a pretreatment material; the alkaline substance accounts for 0.5-5 wt% of the mass of the screened and impurity-removed gypsum raw material;

(2) preheating the pretreatment material to 60-110 ℃, adding a regulating medium after the water content is less than 10 wt%, carrying out fluidized roasting at 120-550 ℃ for 5-180 min through hot gas treatment, removing part of crystal water to obtain roasted gypsum, and discharging gas generated by fluidized roasting after dust removal; the temperature of the hot gas is 120-950 ℃, and the gas velocity is 0.01-10 m/s; the regulating medium comprises any one of air, water vapor, water or nitrogen or a combination of at least two of the air, the water vapor, the water and the nitrogen;

(3) and (3) mixing the calcined gypsum obtained in the step (2) with an additive to obtain a gypsum finished product.

As a preferred technical solution of the present invention, when the gypsum raw material is any one or a combination of at least two of fibrous gypsum ore, lamellar gypsum ore and waste gypsum mold, the method comprises the following steps:

(1) crushing and screening the gypsum raw material to remove impurities to obtain a pretreatment material

(2) Carrying out fluidized roasting on the pretreated material at 120-800 ℃ for 5-180 min to remove part of crystal water to obtain roasted gypsum, and discharging gas generated by fluidized roasting after dedusting; the temperature of the hot gas is 120-950 ℃, the gas speed is 0.01-10 m/s, and the regulating medium comprises any one or the combination of at least two of air, water vapor, water or nitrogen;

In a third aspect, the invention provides a method for comprehensively utilizing gypsum raw materials, which is carried out by adopting the device for comprehensively utilizing gypsum raw materials of the first aspect.

The method for comprehensively utilizing the gypsum raw material provided by the invention is carried out by adopting the device for comprehensively utilizing the gypsum raw material in the first aspect, can better realize continuous production, and has stable product quality.

Preferably, the method comprises the steps of:

(1') the gypsum raw material enters a pretreatment unit for pretreatment to obtain a pretreatment material;

(2') the pretreated material enters a fluidized roasting unit for fluidized roasting, the gas after fluidized roasting enters a dust removal unit for dust removal and then is discharged, and the solid phase after fluidized roasting is roasted gypsum;

and (3 ') feeding the semi-hydrated gypsum in the step (2') into a finished product unit, and blending a finished product to obtain a gypsum finished product.

Preferably, the pretreated material in step (2') enters a preheating unit for preheating and then enters a fluidized roasting unit for fluidized roasting.

Preferably, the gas generated by the preheating unit enters the dust removal unit for dust removal and then is discharged.

Preferably, the hot gas is provided by a heat supply unit.

The heating mode of hot gas in the heat supply unit is combustion heating or electric heating, or direct combustion is adopted to generate hot flue gas. The fuel of the combustion system can be one or more of coal gas, coal, natural gas, methane and fuel oil or a combination of two or more of the coal gas, the natural gas, the methane gas and the fuel oil, wherein typical non-limiting combinations are the combination of the coal gas and the natural gas, the combination of the coal gas and the fuel oil, and the like.

Preferably, the hot gas is hot flue gas generated by burning coal gas, natural gas or methane.

(1') feeding a gypsum raw material into a pretreatment unit, and performing crushing, screening, impurity removal and pH adjustment to obtain a pretreatment material; the pH adjustment comprises: mixing the gypsum raw material after screening and impurity removal with an alkaline substance to obtain a pretreatment material; the alkaline substance accounts for 0.5-5 wt% of the mass of the screened and impurity-removed gypsum raw material;

(2') preheating the pretreated material in a preheating unit to 60-110 ℃, introducing the preheated material into a fluidized roasting unit after the water content is less than 10 wt%, adding a regulating medium, carrying out fluidized roasting at 120-550 ℃ for 5-180 min under the action of hot gas, and removing part of crystal water to obtain roasted gypsum; gas generated by fluidized roasting is discharged after dust removal; the temperature of the hot gas is 120-950 ℃, the gas velocity is 0.01-10 m/s, and the regulating medium comprises any one or the combination of at least two of air, water vapor, water or nitrogen; gas generated by the preheating unit enters the dust removal unit for dust removal and then is discharged, and the hot gas is provided by the heat supply unit;

(3 ') putting the calcined gypsum obtained in the step (2') into a finished product unit, and mixing and blending the calcined gypsum with an additive to obtain a gypsum finished product.

Compared with the prior art, the invention has at least the following beneficial effects:

(1) the device for comprehensively utilizing the gypsum raw material can realize comprehensive utilization of solid waste and reduce environmental pollution of solid waste stacking to soil, water and atmosphere.

(2) The device for comprehensively utilizing the gypsum raw material provided by the invention adopts a fluidized bed technology, has the advantages of large reaction area, high reaction rate, uniform heating, small occupied area and no phenomena of excessive roasting or insufficient roasting, and the prepared building gypsum has high dihydrate gypsum conversion rate and stable quality. When the semi-hydrated gypsum is prepared, the content of the anhydrous gypsum and the dihydrate gypsum is less than 1 wt%, and the content of the semi-hydrated gypsum is more than or equal to 85 wt%.

(3) The method for comprehensively utilizing the gypsum raw material provided by the invention can realize flexible and timely adjustment of the atmosphere and the temperature in the roasting process by adopting the regulating medium.

(4) The method for comprehensively utilizing the gypsum raw material provided by the invention preheats the material by adopting the roasted tail gas and/or hot gas, and fully recovers the heat in the process.

(5) The method for comprehensively utilizing the gypsum raw material can realize continuous production and is convenient for large-scale production.

Drawings

FIG. 1 is a schematic view of an apparatus for comprehensive utilization of gypsum raw material provided in example 1 of the present invention.

Figure 2 is an XRD pattern of the phosphogypsum raw material used in example 1 of the present invention.

FIG. 3 is a schematic view of an apparatus for comprehensive utilization of gypsum raw material provided in example 2 of the present invention.

FIG. 4 is a schematic view of an apparatus for comprehensive utilization of gypsum raw material provided in example 3 of the present invention.

In the figure: 1-a pre-treatment unit; 2-a preheating unit; 3-fluidized roasting unit; 4-a finished product unit; 5-a heat supply unit; 6-dust removal unit.

Detailed Description

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

The present invention is described in further detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.

First, an embodiment

Example 1

The embodiment provides a device for comprehensively utilizing gypsum raw materials, which comprises a pretreatment unit 1, a preheating unit 2, a fluidized roasting unit 3 and a finished product unit 4 which are connected in sequence as shown in fig. 1.

The device for comprehensively utilizing the gypsum raw materials also comprises a dust removal unit 6 connected with the fluidized roasting unit 3 and a heat supply unit 5 connected with the fluidized roasting unit 3.

The pretreatment unit 1 comprises a feed inlet, a regulator inlet and an impurity discharge port, and specifically comprises a squirrel-cage crusher, a screening and impurity removing device and a pH adjusting device.

A screw feeder is arranged between the pretreatment unit 1 and the preheating unit 2.

The fluidized roasting unit 3 comprises a first gas outlet, the first gas outlet is connected with the preheating unit 2, the fluidized roasting unit 3 comprises a regulating medium inlet, and specifically, the fluidized roasting unit 3 comprises a bubbling fluidized bed, a temperature regulating medium buffer tank, a connecting pipeline and a control system.

The dust removal unit 6 comprises a solid outlet, the solid outlet is connected with the fluidization roasting unit 3, the dust removal unit 6 comprises a tail gas outlet, and the dust removal unit 6 comprises a bag-type dust remover and a draught fan which are sequentially connected.

The finished product unit 4 comprises an additive inlet and a finished product outlet; specifically, the finished product unit 4 comprises an intermittent stirring kettle, a metering hopper, a bagging machine and a stacking robot.

The heat supply unit 5 is also connected with the preheating unit 2; the heat supply unit 5 comprises an air inlet and a fuel inlet; specifically, the heat supply unit 5 comprises a fan, a fuel tank and a hot blast stove, wherein the fuel tank is provided with an air inlet and a fuel inlet.

The preheating unit 2 comprises a second gas outlet, the second gas outlet is connected with the dust removal unit 6, and the preheating unit 2 is composed of a 3-stage cyclone preheater.

The embodiment also provides a method for comprehensively utilizing gypsum raw materials, which comprises the following steps:

(1) the phosphogypsum enters a pretreatment unit 1 and is crushed, screened to remove impurities and subjected to pH adjustment to obtain a pretreatment material; the pH is adjusted as follows: mixing the screened and impurity-removed phosphogypsum with 2 wt% of calcium oxide (the calcium oxide accounts for the mass percentage of the screened and impurity-removed phosphogypsum), and adjusting the pH value to 5 to obtain a pretreatment material;

(2) the pretreatment material enters a preheating unit 2 from a screw feeder to be preheated to 90 ℃, enters a fluidized roasting unit 3 after the water content is less than 10 wt%, is added with a regulating medium, is subjected to fluidized roasting at 170 ℃ for 60min through hot gas treatment, and removes part of crystal water to obtain semi-hydrated gypsum; the regulating medium is water vapor;

the temperature of the hot gas is 450 ℃, and the gas velocity is 5 m/s;

air enters the heat supply unit 5 from an air inlet and fuel enters the preheating unit 2 and the fluidized roasting unit 3 respectively to supply heat after combustion, gas generated by fluidized roasting enters the preheating unit 2 to be preheated, energy consumption is saved, the gas generated by the preheating unit 2 enters the dust removal unit 6 to remove dust, then the solid part returns to the fluidized roasting unit 3, and the gas part is discharged in a tail gas form;

(3) and (3) putting the calcined gypsum obtained in the step (2) into a finished product unit 4, and mixing and blending the calcined gypsum with expanded perlite, cement and quartz sand to obtain the light plastering gypsum mortar.

In this example, the phosphogypsum (XRF composition analysis of phosphogypsum is shown in table 1, and XRD phase diagram is shown in fig. 2), as can be seen from fig. 2 and table 1, the main component of phosphogypsum is calcium sulfate dihydrate, and the phosphogypsum is calcined at 170 ℃ under the control of a temperature adjusting medium to obtain hemihydrate gypsum, and the composition of the hemihydrate gypsum is shown in table 2, the content of the hemihydrate gypsum is 89.3 wt%, no anhydrous gypsum is detected, and the content of the dihydrate gypsum is only 0.1 wt%. The roasting is uniform in the process, the product quality is stable, and the overburning phenomenon does not exist; the preheating unit 2 reasonably recycles the waste heat in the process, so that the heat utilization rate is improved; the roasting temperature is flexibly adjusted.

TABLE 1

Name (R)	Content (wt%)
		SO ₃	54.126
CaO	35.083
		F	3.531
SiO ₂	2.629
		K ₂ O	2.265
P ₂ O ₅	0.854
		Al ₂ O ₃	0.759
Fe ₂ O3	0.475
		MgO	0.075
TiO ₂	0.073
		SrO	0.072
Na ₂ O	0.048
		MnO	0.008

Example 2

The embodiment provides a device for comprehensively utilizing gypsum raw materials, which comprises a pretreatment unit 1, a preheating unit 2, a fluidized roasting unit 3 and a finished product unit 4 which are connected in sequence as shown in fig. 3.

The device for comprehensively utilizing the gypsum raw materials also comprises a dust removal unit 6 connected with the fluidized roasting unit 3.

Pretreatment unit 1 includes feed inlet, regulator entry and impurity discharge port, specifically includes impact crusher and screening edulcoration device.

The fluidized roasting unit 3 comprises a first gas outlet, the first gas outlet is connected with the preheating unit 2, the fluidized roasting unit 3 comprises a regulating medium inlet, an air inlet and a fuel inlet, the fluidized roasting unit 3 specifically comprises a bubbling fluidized bed with a combustion chamber, a temperature regulating medium buffer tank, a connecting pipeline and a control system, the bubbling fluidized bed with the combustion chamber is provided with the regulating medium inlet, and the combustion chamber of the bubbling fluidized bed with the combustion chamber is provided with the air inlet and the fuel inlet.

The dust removal unit 6 comprises a solid outlet, the solid outlet is connected with the fluidization roasting unit 3, the dust removal unit 6 comprises a tail gas outlet, and the dust removal unit 6 comprises a 1-level cyclone separator, a bag-type dust remover and a draught fan which are sequentially connected.

The preheating unit 2 comprises a second gas outlet, the second gas outlet is connected with the dust removal unit 6, and the preheating unit 2 is composed of a fluidized bed preheater.

(1) the layered gypsum ore enters a pretreatment unit 1, and is crushed, screened and purified to obtain a pretreatment material;

(2) the pretreatment material enters a preheating unit 2 from a screw feeder to be preheated to 60 ℃, enters a fluidized roasting unit 3 after the water content is less than 10 wt%, is added with a regulating medium, is subjected to hot gas treatment and fluidized roasting at 140 ℃ for 120min, and removes part of crystal water to obtain semi-hydrated gypsum; the regulating medium is air;

the temperature of the hot gas is 250 ℃, and the gas velocity is 2 m/s;

air enters a combustion chamber of the fluidized roasting unit 3 from an air inlet and fuel from a fuel inlet, hot gas generated after combustion supplies heat for fluidized roasting, the gas generated by the fluidized roasting enters the preheating unit 2 for preheating, energy consumption is saved, after the gas generated by the preheating unit 2 enters the dust removal unit 6 for dust removal, a solid part returns to the fluidized roasting unit 3, and a gas part is discharged in a tail gas form;

(3) and (3) putting the semi-hydrated gypsum obtained in the step (2) into a finished product unit 4, and mixing and blending the semi-hydrated gypsum with expanded perlite, cement and quartz sand to obtain the light plastering gypsum mortar.

In this example, the layered gypsum ore was calcined at 140 ℃ under the control of a temperature adjusting medium to obtain hemihydrate gypsum, and the composition of the hemihydrate gypsum was determined to be shown in table 2, wherein the content of the hemihydrate gypsum was 89.2 wt%. The roasting is uniform in the technical process, and the overburning phenomenon does not exist; the preheating unit 2 reasonably recycles the waste heat in the process, so that the heat utilization rate is improved; the roasting temperature is flexibly adjusted. The fluidized roasting unit 3 is provided with a combustion chamber, so that the process flow is simplified.

Example 3

The embodiment provides a device for comprehensively utilizing gypsum raw materials, which comprises a pretreatment unit 1, a fluidized roasting unit 3 and a finished product unit 4 which are connected in sequence as shown in fig. 4.

The pretreatment unit 1 comprises a feed inlet, a regulator inlet and an impurity discharge port, and specifically comprises a cone crusher and a screening and impurity removing device.

The fluidized roasting unit 3 comprises a first gas outlet, the first gas outlet is connected with the dust removal unit 6, the fluidized roasting unit 3 comprises a regulating medium inlet, and specifically, the fluidized roasting unit 3 comprises a vibrating fluidized bed, a temperature regulating medium buffer tank, a connecting pipeline and a control system.

The dust removal unit 6 comprises a solid outlet, the solid outlet is connected with the fluidization roasting unit 3, the dust removal unit 6 comprises a tail gas outlet, and the dust removal unit 6 comprises a 2-level cyclone separator, a bag-type dust remover and a draught fan which are sequentially connected.

The finished product unit 4 comprises an additive inlet and a finished product outlet; the finished product unit 4 specifically comprises an intermittent stirring kettle, a metering hopper and a storage tank.

The heat supply unit 5 comprises an air inlet and a fuel inlet; specifically, the heat supply unit 5 comprises a fan, a coal bunker, a coal-fired boiler and a ceramic filter, wherein an air inlet is formed in the coal-fired boiler, and a fuel inlet is formed in the coal bunker.

(1) the layered gypsum ore enters a pretreatment unit 1 and is crushed to obtain a pretreatment material;

(2) the pretreatment material enters a preheating unit 2 from a screw feeder to be preheated to 70 ℃, enters a fluidized roasting unit 3 after the water content is less than 10 wt%, is added with a regulating medium, is subjected to fluidized roasting at 150 ℃ for 5min through hot gas treatment, and removes part of crystal water to obtain semi-hydrated gypsum; the regulating medium is air;

the temperature of the hot gas is 850 ℃, and the gas velocity is 10 m/s;

air enters the heat supply unit 5 from an air inlet and fuel from a fuel inlet, hot gas generated after combustion enters the fluidized roasting unit 3 for heat supply, the gas generated by fluidized roasting enters the dust removal unit 6 for dust removal, part of the gas returns to the fluidized roasting unit 3, and part of the gas is discharged in a tail gas form;

(3) and (3) allowing the semi-hydrated gypsum obtained in the step (2) to enter a finished product unit 4, and mixing and blending the semi-hydrated gypsum with expanded perlite, cement and quartz sand to obtain the light plastering gypsum mortar.

In this example, the layered gypsum ore was calcined at 150 ℃ under the control of a temperature adjusting medium to obtain hemihydrate gypsum, and the composition of the hemihydrate gypsum was determined to be shown in table 2, wherein the content of the hemihydrate gypsum was 89.5 wt%. The roasting temperature in the process is flexibly adjusted, the roasting is uniform, and the overburning phenomenon does not exist.

Example 4

This example provides a comprehensive utilization apparatus for gypsum raw materials, which is the same as in example 1 except that "the first gas outlet of the fluidized roasting unit is connected to the dust removal unit".

In the embodiment, the phosphogypsum is calcined at 170 ℃ under the regulation and control of a temperature regulating medium to obtain the hemihydrate gypsum. The technical process has uniform roasting, stable product quality and no overburning phenomenon, and the composition of the semi-hydrated gypsum is detected to be shown in the table 2, wherein the content of the semi-hydrated gypsum is 87.6 wt%; however, compared with example 1, the gas of the fluidized roasting unit directly enters the dust removal unit for dust removal treatment, and the heat utilization rate is poorer than that of example 1, thereby showing that the first gas outlet is preferably connected with the preheating unit, and the heat utilization rate is improved.

Example 5

The embodiment provides a method for comprehensively utilizing gypsum raw materials, which is implemented by adopting the device provided in embodiment 2, and specifically comprises the following steps:

(1) the layered gypsum ore enters a pretreatment unit, and is crushed, screened and purified to obtain a pretreatment material;

(2) the pretreatment material enters a preheating unit from a screw feeder to be preheated to 110 ℃, after the water content is 8 wt%, the pretreatment material enters a fluidized roasting unit, a regulating medium is added, fluidized roasting is carried out at 120 ℃ for 180min through hot gas treatment, and part of crystal water is removed to obtain semi-hydrated gypsum (the composition of which is shown in table 2); the regulating medium is air;

the temperature of the hot gas is 650 ℃, and the gas velocity is 10 m/s;

air enters a combustion chamber of the fluidized roasting unit from an air inlet and fuel from a fuel inlet, hot gas generated after combustion supplies heat for fluidized roasting, gas generated by the fluidized roasting enters a preheating unit for preheating, energy consumption is saved, part of the gas generated by the preheating unit returns to the fluidized roasting unit after entering a dust removal unit for dust removal, and part of the gas is discharged in a tail gas form;

(3) and (3) putting the semi-hydrated gypsum precursor in the step (2) into a finished product unit, and mixing and blending the semi-hydrated gypsum precursor with expanded perlite, cement and quartz sand to obtain the light plastering gypsum mortar.

Second, comparative example

Comparative example 1

This comparative example provides an apparatus for comprehensive utilization of gypsum raw material, which is the same as in example 1 except that the fluidized calcining unit is replaced with a double-drum rotary calcining furnace.

This comparative example also provides a method for the comprehensive utilization of gypsum raw material, which is the same as example 1 except that the calcination in the fluidized calcination unit is replaced with calcination in a double-drum rotary calciner.

Since the double-barrel rotary calciner is adopted in the comparative example 1, the flame-throwing direction of the flame-throwing furnace is towards the open end of the inner barrel of the calciner at one end of the feed port of the calciner, and the high-temperature flue gas is easy to generate an overburning phenomenon when contacting with materials, the composition of the calciner is detected as shown in table 2, the content of the semi-hydrated gypsum is 62 wt%, compared with the example 1, the product is not uniform in calcination and unstable in quality, and the content of the semi-hydrated gypsum is greatly reduced, thereby showing that the stability and the quality of the semi-hydrated gypsum are improved by adopting a fluidization technology.

The raw material compositions of phosphogypsum and layered gypsum ore used in the above examples and comparative examples and the composition of hemihydrate gypsum produced in step (2) are shown in table 2.

TABLE 2

Sample (I)	Dihydrate Gypsum (wt%)	Hemihydrate Gypsum (wt%)	Anhydrous gypsum (wt%)
				Phosphogypsum	91.07	0	0
Layered gypsum ore	92.3	0	0
				Example 1	0.1	89.3	0
Example 2	0.5	89.2	0
				Example 3	0.2	89.5	0
Example 4	0.8	87.6	0
				Example 5	0	88	0.2
Comparative example 1	11	62	17

The method for comprehensively utilizing the gypsum raw materials is not limited to the phosphogypsum and the layered gypsum mine exemplified in the embodiment, is limited by space, is not exemplified any more, and can prepare high-purity hemihydrate gypsum by adopting any one or the combination of at least two of gypsum such as desulfurized gypsum, gypsum mine waste, citric acid gypsum, fluorgypsum, salt gypsum, monosodium glutamate gypsum, copper gypsum, titanium gypsum, boron gypsum, waste gypsum, fibrous gypsum mine or waste gypsum mold and the like.

In conclusion, the device for comprehensively utilizing the gypsum raw materials has the advantages that the fluidized roasting unit is adopted, so that the reaction area is large, the reaction rate is high, the heating is uniform, and the occupied area is small; the phenomenon of over-roasting or under-roasting is avoided, and the roasted tail gas is discharged after dust removal, so that no dust pollution exists; the method for comprehensively utilizing the gypsum raw material can realize comprehensive utilization of solid waste, reduces environmental pollution of solid waste stacking to soil, water and atmosphere, has stable product quality, has the content of semi-hydrated gypsum of more than or equal to 85wt percent and the total content of dihydrate gypsum and anhydrous gypsum of less than 1wt percent, and has good popularization and application values.

The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must be implemented depending on the above detailed structural features. It should be understood by those skilled in the art that any modifications of the present invention, equivalent substitutions of selected components of the present invention, additions of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims

1. A method for comprehensively utilizing gypsum raw materials is characterized in that a device for comprehensively utilizing gypsum raw materials adopted by the method for comprehensively utilizing gypsum raw materials comprises a pretreatment unit, a fluidized roasting unit and a finished product unit which are sequentially connected; the device also comprises a preheating unit arranged between the pretreatment unit and the fluidized roasting unit; the fluidized roasting unit comprises a first gas outlet;

the first gas outlet is connected with the preheating unit; the fluidized roasting unit comprises a regulating medium inlet;

the device for comprehensively utilizing the gypsum raw materials also comprises a dust removal unit connected with the fluidized roasting unit;

the method comprises the following steps:

(1) pretreating a gypsum raw material to obtain a pretreated material;

(2) preheating the pretreatment material to 60-110 ℃, adding a regulating medium after the water content is less than 10 wt%, carrying out fluidized roasting at 120-550 ℃ for 5-180 min through hot gas treatment, carrying out chemical reaction under the action of hot gas, removing part of crystal water to obtain a gypsum precursor, and discharging gas generated by fluidized roasting after dust removal; the temperature of the hot gas is 120-950 ℃, and the gas velocity is 0.01-10 m/s; the regulating medium comprises any one or the combination of at least two of air, water vapor, water or nitrogen;

in the preheating process, gas generated by the fluidized roasting in the step (2) is heated, or hot gas and the gas generated by the fluidized roasting in the step (2) are heated, the gas generated by the fluidized roasting is discharged after heat recovery and dust removal, and the solid phase after the fluidized roasting is roasted gypsum; the calcined gypsum is semi-hydrated gypsum;

(3) and (3) blending the calcined gypsum and the additive in the step (2) to obtain a gypsum finished product.

2. The method of claim 1, wherein the pretreatment unit comprises a feed inlet.

3. The method of claim 1, wherein the pretreatment unit comprises a conditioner inlet.

4. The method of claim 1, wherein the pretreatment unit comprises an impurity drain.

5. The method of claim 1, wherein the fluidizing torrefaction unit includes an air inlet and a fuel inlet.

6. The method of claim 1, wherein the dedusting unit includes a solids outlet.

7. The method of claim 6, wherein the solids outlet is connected to the fluidizing torrefaction unit.

8. The method of claim 1, wherein the dust removal unit comprises an off-gas outlet.

9. The method of claim 1, wherein the finished unit includes an additive inlet and a finished product outlet.

10. The method of claim 1, wherein the means for recycling the gypsum feedstock further comprises a heat supply unit coupled to the fluidized roasting unit.

11. The method according to claim 10, wherein the heat supply unit is further connected to the preheating unit.

12. The method of claim 1, wherein the preheating unit comprises a second gas outlet.

13. The method of claim 12, wherein the second gas outlet is connected to the dedusting unit.

14. The method of claim 10, wherein the heat supply unit comprises an air inlet and a fuel inlet.

15. The method of claim 1, wherein the pretreatment unit comprises a crushing device.

16. The method of claim 15, wherein the pre-processing unit further comprises a neutralization device.

17. The method of claim 1, wherein the fluidized roasting unit comprises a fluidized roasting apparatus.

18. The method of claim 17, wherein the fluidized roasting apparatus comprises any one of a riser, a bubbling fluidized bed, a stirred fluidized bed, or a vibrating fluidized bed, or a combination of at least two thereof.

19. The method according to claim 1, wherein the preheating unit comprises a 1-3 stage cyclone preheater and/or a fluidized bed preheater.

20. The method according to claim 1, wherein the gypsum raw material in step (1) comprises any one of phosphogypsum, desulfurized gypsum, gypsum mine waste, citric gypsum, fluorgypsum, salt gypsum, gourmet gypsum, copper gypsum, titanium gypsum, boron gypsum, waste gypsum material, fibrous gypsum ore, layered gypsum ore or waste gypsum mold or a combination of at least two of them.

21. The method of claim 1, wherein the pre-processing comprises: the gypsum raw material is subjected to any one or the combination of at least two of crushing, screening and impurity removal or pH adjustment to obtain a pretreatment material.

22. The method of claim 21, wherein the pH adjustment comprises: mixing the gypsum raw material with a regulator to obtain a pretreatment material.

23. The method of claim 22, wherein the conditioning agent comprises an alkaline substance.

24. The method of claim 23, wherein the alkaline material comprises quicklime and/or slaked lime.

25. The method according to claim 22, wherein the regulator accounts for 0.5-5 wt% of the mass of the screened and impurity-removed gypsum raw material.

26. The method of claim 1, wherein the hot gas comprises any one or a combination of at least two of post-dedusting flue gas, air, nitrogen, or water vapor.

27. The method according to claim 1, wherein the gypsum finished product in the step (3) comprises any one of floor gypsum, instant wall gypsum, plastering gypsum, gypsum blocks, cement retarder or light plastering mortar.

28. Method according to claim 1, characterized in that it comprises the following steps:

(2) preheating the pretreatment material to 60-110 ℃, adding a regulating medium after the water content is less than 10 wt%, carrying out fluidized roasting at 120-550 ℃ for 5-180 min through hot gas treatment, removing part of crystal water to obtain a gypsum precursor, and discharging gas generated by fluidized roasting after dust removal; the temperature of the hot gas is 120-950 ℃, and the gas velocity is 0.01-10 m/s; the regulating medium comprises any one or the combination of at least two of air, water vapor, water or nitrogen;