CN112551925B - Device and method for comprehensive utilization of gypsum raw materials - Google Patents

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 comprehensive utilization of gypsum raw materials

technical field

The invention relates to the technical field of gypsum disposal, in particular to a device and method for comprehensive utilization of gypsum raw materials.

Background technique

The main methods of processing gypsum raw materials into hemihydrate gypsum are calcination method and high temperature flash sintering method. The calcination method is the main method for producing hemihydrate gypsum at present. This method does not wash with water, which avoids the waste of water resources and secondary pollution.

The techniques disclosed in RU2005119689A, PL2013000019W, EP15752713.6, US15119688, RU2007101877A, and GB2028783A all add different additives and ash to phosphogypsum, and burn the cement clinker through a rotary furnace.

GB2605072A discloses a method for roasting hemihydrate gypsum in a rotary kiln at 200-240 °C; the international patent PCT/CN2017/112084 applied by Zhengzhou Sandi Construction Technology Co., Ltd. adopts preheating drum, calcining drum, reduction drum, etc. Hemihydrate gypsum is obtained by calcining phosphogypsum.

GB2028783A discloses a method for preparing gypsum by subjecting phosphogypsum to a two-stage heat treatment and adding lime, the first stage is dehydration at a temperature of 110 to 150 degrees Celsius for 30 to 90 minutes, and the second stage is 130 to 180 degrees Celsius for a duration of A conditioning of 10 minutes to several hours produces gypsum.

It can be seen that the prior art mainly uses rotary kiln, rotary furnace, boiling furnace, etc. to prepare hemihydrate gypsum, which has long calcination time, large equipment area and high operating energy consumption.

CN1594175A discloses an internal heating gypsum construction process method. A boiling furnace is used to provide heat source, and the calcination system adopts an internal heating rotary kiln with a lifting plate. The material is lifted by the lifting plate to enhance heat transfer, and the thermal efficiency can reach 49-61%. The thermal efficiency of phosphogypsum roasting is improved.

CN104310830A discloses a method for producing β-high-purity gypsum powder from phosphogypsum, which adopts an FC sub-chamber calciner to indirectly exchange heat with hot flue gas in a heat exchange tube. Heat utilization is low.

CN207468502U discloses a suspended airflow type phosphogypsum integrated processing device, and CN107651870A discloses a suspended airflow type phosphogypsum integrated processing device and method, including a drying unit, a high temperature impurity removal unit, a calcination unit and a cooling unit. The phosphogypsum is dried by hot air at a gas velocity of 15-25m/s and a temperature of 400-500°C, and then enters the impurity removal furnace to remove impurities under the action of hot air at 450-800°C, and then calcined at 110-220°C hot air. In this process, there are many high-temperature flue gases interacting with phosphogypsum, which is prone to excessive dehydration and anhydrite resulting in overburning. The impurity removal furnace and the phase change furnace have inner and outer cylinder structures, and the reaction time of materials and gases in the furnace is not easy to control.

CN107902932A discloses a phosphogypsum calcining device, the device is composed of two preheating drums, two calcining drums, and a reducing drum, and each drum is conveyed by a conveying device. The preheating adopts calcining tail gas and material to indirectly contact the drying material in the preheating drum, which effectively avoids the disadvantage that the high water content of the calcining tail gas will affect the removal of free water of the material. However, the maximum diameter of the drum is 3.3 meters. It can be seen that these drums require more power to operate. Although the construction cost is low, the operating cost is high. In addition, the solid material is deposited on the bottom of the drum by gravity, although the drum rotation cannot improve the uniformity of the reaction process.

CN110092599A discloses a phosphogypsum calcining system, which includes a calcining furnace, a fire-spraying furnace, a settling chamber, a front dust collector, a preheating furnace, a rear dust collector, a reduction furnace and a draft fan. Among them, the preheating furnace is a through-core tubular rotary kiln, and the calcining furnace is a double-cylinder rotary calcining furnace. The flame-throwing furnace is located at one end of the feeding port of the calcining furnace, and the flame-throwing direction is toward the open end of the inner cylinder of the calcining furnace. The high-temperature flue gas is prone to over-burning when it contacts the material. The rotary kiln consumes a lot of power and occupies a large area.

CN110143773A discloses a phosphogypsum calcining system, which includes a calcining furnace, a flame-spraying furnace, a rear dust collector, a front dust collector, a preheating furnace, a reduction furnace, a settling chamber, and an induced draft fan. Reasonable layout of each calcining equipment, compact structure, rational utilization of waste heat, and simplified hot air circulation structure. The technology uses a double-barrel rotary calciner.

CN201614351U discloses an integrated device for waste heat utilization of a phosphogypsum modified boiling furnace, including a boiling furnace, a rotary kiln, bag dust removal and waste heat reuse. The coal of the device is burned in the boiling furnace, and the flue gas enters the rotary kiln to modify and calcine the phosphogypsum. The coal combustion flue gas of the device enters the rotary kiln and the flue gas dust directly enters the phosphogypsum to increase the impurity content.

CN203878066U discloses an FC furnace drying and calcining system. The system includes a coal-fired boiling furnace to generate flue gas into the FC calciner, and the flue gas and raw gypsum are indirectly in contact with the raw gypsum through a metal transfer heat pipe, which avoids the fact that the fly ash is mixed into the finished gypsum powder when the heat source is in direct contact with the raw gypsum. The blower air enters the FC calciner to blow the raw gypsum powder to enhance the heat exchange effect, but the indirect heat exchange efficiency is lower than the direct contact heat exchange.

CN208414262U discloses a new type of phosphogypsum calcining equipment, which adopts an inner heat pipe type rotary kiln, and the flue gas is introduced into the inner heat pipe to indirectly contact the phosphogypsum, so as to ensure heat transfer and the flue gas does not pollute the raw materials. The equipment still uses a rotary kiln, because the heat pipe is in the center of the rotary kiln and the material sinks at the bottom of the rotary kiln, resulting in insufficient heat exchange and uneven roasting of phosphogypsum.

CN208346051U discloses a system for preparing building gypsum powder by using phosphogypsum. The system includes a loader, a dryer, a calciner, a bucket elevator, a heat source device and a waste gas treatment device. The dryer is a two-cylinder rotary dryer with a length of 20 meters and a drying temperature of 400-500 °C. The calciner is a three-cylinder calciner at 170°C. The system filters the flue gas with ceramic dust removal equipment and then uses it in the roasting process, which reduces the fly ash content mixed with building gypsum. The large-scale rotary equipment is used as the main drying and roasting equipment, which occupies a large area and is not easy to be used in the processing process with large processing capacity, and the operating cost is high.

CN108658484A discloses a staged treatment process for building gypsum. After drying the phosphogypsum in a hot-air drying furnace at 390-410°C for 15s, the phosphogypsum is heated to 100°C in a tunnel furnace and then heated in a rotary heating furnace at 190-200°C for 20- 30min. The material is ball-milled to obtain plaster of construction. The process adopts tunnel kiln and rotary heating furnace, which occupies a large area and has high equipment operation and maintenance costs.

CN207175793U discloses a device for preparing building gypsum from phosphogypsum. Phosphogypsum and lime are processed in a retting kiln and then enter a rotary calcining kiln for calcination, and then the materials are cooled and ground to obtain building gypsum. The heat source of the device is the hot air generated by the boiling furnace and the phosphogypsum to calcine the phosphogypsum in the rotary calcining kiln.

CN204417351U discloses a phosphogypsum calcining system with a flash dryer, the system uses a flash dryer and a rotary kiln to dry and roast materials, and the process optimizes the utilization of hot gas. The flue gas generated by the combustion chamber enters the rotary kiln and is in direct contact with the phosphogypsum.

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

To sum up, the existing technology mainly adopts the rotary kiln to exchange heat directly with the hot gas, or adopts the indirect heat exchange method of the heat exchange tube for calcination. It consumes a lot and occupies a large area. Some use a sub-chamber calciner with a heat exchange tube for calcination, the calcination time is long, and the utilization rate of indirect heat exchange heat is low. This results in low output per line, high energy consumption and serious dust pollution. The quality of the hemihydrate gypsum produced is unstable and cannot meet the requirements of the downstream gypsum cementitious material industry such as gypsum board, gypsum strip, fiber-reinforced gypsum board, gypsum block or gypsum mortar.

Therefore, there is an urgent need to develop a new device and method for preparing hemihydrate gypsum.

SUMMARY OF THE INVENTION

In view of the problems existing in the prior art, the present invention provides a device and method for comprehensive utilization of gypsum raw materials, the device and method process uniformly roasting, product quality is stable, and there is no over-burning phenomenon; the waste heat in the process can be reasonably recycled , the utilization rate of heat is improved; the roasting temperature can be adjusted flexibly; the roasted gypsum can be effectively and comprehensively utilized by industrial by-product gypsum to achieve the purpose of resource utilization of solid waste.

For this purpose, the present invention adopts the following technical solutions:

In the first aspect, the present invention provides a device for comprehensive utilization of gypsum raw materials, the device for comprehensive utilization of gypsum raw materials includes a pretreatment unit, a preheating unit, a fluidized roasting unit and a finished product unit connected in sequence; the device also Including a dedusting unit connected to the fluidized roasting unit.

The fluidized roasting unit in the device for comprehensive utilization of gypsum raw materials provided by the present invention can provide a stable temperature field, and the material contacts the gas phase in a fluidized form, which can effectively prevent over-firing, and the roasting temperature can be flexibly adjusted; In addition, the gas generated by the fluidized roasting unit is dedusted by the dedusting unit and then discharged in the form of tail gas, which effectively alleviates the problem of dust pollution, and the quality of the prepared hemihydrate gypsum and gypsum products is stable.

Preferably, the pretreatment unit includes a feed port.

Preferably, the pretreatment unit includes a conditioner inlet.

Preferably, the pretreatment unit includes an impurity discharge port.

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

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

When the device includes a preheating unit, preferably the first gas outlet is connected to the preheating unit, and the waste heat of the gas after fluidized roasting is used to preheat the material, thereby improving the heat utilization rate.

Preferably, the fluidized roasting unit includes a regulating medium inlet.

Preferably, the fluidized roasting unit includes an air inlet and a fuel inlet.

When the device does not include a heating unit, the fluidized roasting device used in the fluidized roasting unit may have its own combustion chamber, and the combustion chamber is provided with an air inlet and a fuel inlet. The process flow Shorter and saves floor space.

Preferably, the dedusting unit includes a solids outlet.

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

Preferably, the dust removal unit includes an exhaust gas outlet.

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

Preferably, the device further comprises a preheating unit arranged 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 mold, the pretreatment unit may not be provided.

Preferably, the device for comprehensive utilization of gypsum raw materials further includes a heating unit connected to the fluidized roasting unit.

Preferably, the heating unit is also connected with the preheating unit.

The hot gas delivery of the heating unit and the preheating unit can be mixed with the gas produced by the fluidized roasting unit and then sent to the preheating unit, or can be sent to the preheating unit separately.

Preferably, the preheating unit includes a second gas outlet.

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

Preferably, the heating unit includes an air inlet and a fuel inlet.

Preferably, the pretreatment unit includes a crushing device.

Preferably, the crushing device includes 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 preprocessing unit further includes a neutralization device.

The neutralization device of the invention can adjust the pH value of the gypsum raw material, which is beneficial to the subsequent preparation of hemihydrate gypsum.

Preferably, the fluidized roasting unit includes a fluidized roasting device.

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

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

The present invention has no special restrictions on the connection of specific devices in each unit, and any device known to those skilled in the art that can be used to realize various functions can be used. preparation, and the product quality is stable and the dust pollution is small.

In a second aspect, the present invention provides a method for comprehensive utilization of gypsum raw materials, the method comprising the steps of:

(1) gypsum raw material is pretreated to obtain pretreated material;

(2) described pretreatment material is subjected to fluidized roasting, and the gas after described fluidized roasting is discharged after recycling heat and dedusting, and the solid phase after fluidized roasting is roasted gypsum;

(3) The calcined gypsum and additives in step (2) are prepared to obtain a finished gypsum product.

In the method for comprehensive utilization of gypsum raw materials provided by the present invention, fluidized roasting is used to roast the pretreated material, which can maintain the uniform temperature field, humidity and better material fluidization state required for the reaction, and increase the regulation of the roasting process. Flexibility, stable product quality.

Preferably, the gypsum raw materials in step (1) include phosphogypsum, desulfurized gypsum, gypsum mine waste, citric acid gypsum, fluorine gypsum, salt gypsum, monosodium glutamate, copper gypsum, titanium gypsum, boron gypsum, waste gypsum, fiber Any one or a combination of at least two of the gypsum-like gypsum ore, layered gypsum ore or waste gypsum molds, wherein typical non-limiting combinations are the combination of fluorogypsum and monosodium glutamate, the combination of fluorogypsum and fibrous gypsum ore, Combination of fluorogypsum and copper gypsum, combination of monosodium gypsum and fibrous gypsum, combination of fibrous gypsum and phosphogypsum, combination of fibrous gypsum and copper gypsum, combination of copper gypsum and phosphogypsum, phosphogypsum and salt A combination of plaster, etc.

The gypsum raw material of the present invention preferably adopts industrial by-product gypsum, that is, the present invention preferably provides a comprehensive utilization device and method for industrial by-product gypsum, wherein the industrial by-product gypsum includes phosphogypsum, desulfurized gypsum, citric acid gypsum, fluorogypsum, Salt gypsum, monosodium glutamate gypsum, copper gypsum, titanium gypsum, boron gypsum, etc. can not only make full use of these industrial by-product gypsum to reduce environmental pollution, but also prepare hemihydrate gypsum and gypsum products with high stability.

The gypsum raw material of the present invention can also use conventional gypsum ore as the raw material, and can also produce hemihydrate gypsum and gypsum finished products with excellent performance.

Preferably, the pretreatment includes: crushing the gypsum raw material, sieving and removing impurities or pH adjustment, any one or a combination of at least two, to obtain a pretreatment material.

The pretreatment of the present invention has different pretreatment methods according to different raw materials. Specifically, it may be only crushing treatment, or a combination of crushing and screening for impurity removal, or a combination of crushing, screening for impurity removal and pH adjustment , or a combination of fragmentation and pH adjustment, etc.

When the gypsum raw material is a large piece of material, the large piece of gypsum raw material is transformed into a small piece of material through crushing; a screening and impurity removal step can also be added to remove impurities such as large pieces of metal and woven bags.

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

Preferably, the conditioning agent includes an alkaline substance.

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

Preferably, the conditioner accounts for 0.5-5wt% of the quality of the gypsum raw material after sieving and impurity removal, for example, it can be 0.5wt%, 1wt%, 1.2wt%, 1.5wt%, 2wt%, 2.2wt%, 2.5wt% %, 2.8wt%, 3wt%, 3.2wt%, 3.5wt%, 3.8wt%, 4wt%, 4.5wt% or 5wt%, etc., preferably 0.5-3wt%.

Preferably, the pH value after pH adjustment is 4-7, for example, it can be 4, 4.2, 4.5, 4.8, 5, 5.2, 5.5, 5.8, 6, 6.2, 6.5, 6.8 or 7, etc., preferably 4.5- 6.5.

Preferably, in step (2), the preheated material is preheated before fluidized roasting.

Preferably, the preheating comprises: preheating the pretreatment material to a first temperature.

The preheating heat comes from the gas of the heating unit and the fluidized roasting unit. During the preheating process, the hot gas and the water-containing solid material exchange heat rapidly to remove part of the attached water.

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

Preferably, the first temperature is 60-110°C, such as 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C or 110°C, etc. .

Preferably, the water content of the preheated pretreatment material is less than 10wt%, for example, it can be 9.9wt%, 9.8wt%, 9.5wt%, 9.0wt%, 8.9wt%, 8.5wt%, 8wt%, 7wt% % or 6.5wt%, etc.

Preferably, the gas produced by the preheating is discharged after being dedusted.

Preferably, the fluidized roasting in step (2) includes: the pretreatment material in step (1) undergoes a chemical reaction under the action of hot gas to remove part of the crystal water to obtain roasted gypsum.

Preferably, the hot gas includes any one or a combination of at least two of dedusted flue gas, air, nitrogen or water vapor, wherein typical non-limiting combinations are flue gas/nitrogen, air/flue gas or air /Nitrogen combination.

Preferably, the temperature of the hot gas ranges from 120°C to 950°C, such as 120°C, 130°C, 140°C, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C °C, 550 °C, 600 °C, 700 °C, 800 °C, 900 °C or 950 °C, etc.

Preferably, the temperature of the fluidized roasting is 120-550°C, such as 120°C, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, 450°C, 500°C or 550°C, etc. , preferably 135 to 450°C.

Preferably, the fluidized roasting time is 5 to 180 min, for example, it can be 5 min, 10 min, 20 min, 50 min, 80 min, 100 min, 110 min, 120 min, 140 min, 150 min, 160 min or 180 min, etc., preferably 20 to 150 min.

Preferably, the gas velocity in the fluidized roasting process is 0.01-10m/s, for example, it can be 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, 9 m/s or 10 m/s, etc., preferably 0.05 to 7 m/s.

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

The control medium in the present invention can adjust the atmosphere and temperature of the roasting process in time, the temperature field is uniform, and the product quality is stable.

Preferably, the regulating medium comprises any one or a combination of at least two of air, water vapor, water or nitrogen, wherein typical non-limiting combinations are air/water vapor, water/nitrogen or air/nitrogen combination Wait.

Preferably, the treatment of the finished product in step (3) includes: mixing and preparing the calcined gypsum described in step (2) with additives to obtain a finished gypsum product.

Preferably, the gypsum finished product includes any one of floor gypsum quick-wall gypsum, plastering gypsum, gypsum block, cement retarder or light plastering mortar.

As a preferred technical solution of the present invention, the method comprises the following steps:

(1) The gypsum raw material is crushed, screened to remove impurities and pH adjusted to obtain a pretreatment material; the pH adjustment includes: mixing the screened and removed gypsum raw material with an alkaline substance to obtain a pretreated material; the alkali The natural substances account for 0.5-5wt% of the mass of the gypsum raw material after screening and removing impurities;

(2) after the pretreatment material is preheated to 60～110°C, and the water content is less than 10wt%, the regulating medium is added, and the fluidized roasting at 120～550°C is carried out for 5～180min by hot gas treatment, and part of the crystal water is removed to obtain The gypsum is roasted, and the gas produced by the fluidized roasting is discharged after dust removal; the temperature of the hot gas is 120 ℃ ~ 950 ℃, and the gas velocity is 0.01 ~ 10m/s; the regulating medium includes air, water vapor, water or any one or a combination of at least two of nitrogen;

(3) mixing and preparing the calcined gypsum described in step (2) with additives to obtain a finished gypsum 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, layered gypsum ore or waste gypsum mold, the method includes the following steps:

(1) The gypsum raw material is crushed, sieved and impurity removal to obtain pretreatment material

(2) the pretreatment material is fluidized and roasted at 120-800° C. for 5-180 minutes, and part of the crystal water is removed to obtain roasted gypsum, and the gas generated by the fluidized roasting is discharged after dust removal; The temperature is 120℃～950℃, the gas velocity is 0.01～10m/s, and the regulating medium includes any one or a combination of at least two of air, water vapor, water or nitrogen;

(3) mixing and preparing the calcined gypsum described in step (2) with additives to obtain a finished gypsum product.

In a third aspect, the present invention provides a method for comprehensive utilization of gypsum raw materials, which is performed by using the device for comprehensive utilization of gypsum raw materials described in the first aspect.

The method for comprehensive utilization of gypsum raw materials provided by the present invention adopts the device for comprehensive utilization of gypsum raw materials described in the first aspect, which can better realize continuous production and stable product quality.

Preferably, the method comprises the steps of:

(1') gypsum raw material enters the pretreatment unit and is pretreated to obtain pretreatment material;

(2') described pretreatment material enters fluidized roasting unit and carries out fluidized roasting, and the gas after described fluidized roasting enters into dedusting unit and discharges after dedusting, and the solid phase after fluidized roasting is calcined gypsum;

(3') The hemihydrate gypsum described in step (2') enters the finished product unit and after the finished product is deployed, the gypsum finished product is obtained.

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

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

Preferably, the hot gas is provided by a heating unit.

The heating method of the hot gas in the heating unit of the present invention is combustion heating or electric heating, or direct combustion is used to generate hot flue gas. The fuel of the combustion system can be one or more of coal gas, coal, natural gas, biogas and fuel oil, or a combination of two or more of them, wherein a typical non-limiting combination is a combination of coal gas and natural gas, coal and fuel oil, etc.

Preferably, the hot gas is hot flue gas produced by combustion of coal gas, natural gas or biogas.

As a preferred technical solution of the present invention, the method comprises the following steps:

(1') The gypsum raw material enters the pretreatment unit and undergoes crushing, sieving and removing impurities and pH adjustment to obtain a pretreatment material; the pH adjustment includes: mixing the gypsum raw material after sieving and removing impurities with an alkaline substance to obtain a pretreatment material; the alkaline substance accounts for 0.5-5wt% of the mass of the gypsum raw material after sieving and removing impurities;

(2') The pretreatment material enters the preheating unit and is preheated to 60-110°C, and after the water content is less than 10wt%, it enters the fluidized roasting unit, adds a regulating medium, and conducts a flow of 120-550°C under the action of hot gas. State roasting for 5～180min, remove part of crystal water to obtain roasted gypsum; the gas produced by fluidized roasting is discharged after dust removal; the temperature of the hot gas is 120℃～950℃, and the gas velocity is 0.01～10m /s, the regulation medium includes any one or a combination of at least two of air, water vapor, water or nitrogen; the gas generated by the preheating unit enters the dust removal unit for dust removal and is discharged, and the hot gas is discharged by the supply Thermal unit provides;

(3') The calcined gypsum described in step (2') enters the finished product unit and is mixed with additives to obtain a gypsum finished product.

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

(1) The device for comprehensive utilization of gypsum raw materials provided by the present invention can realize the comprehensive utilization of solid wastes and reduce the environmental pollution of soil, water and atmosphere caused by the stacking of solid wastes.

(2) The device for comprehensive utilization of gypsum raw materials provided by the present invention adopts fluidized bed technology, and has large reaction area, high reaction rate, uniform heating, small footprint, and no excessive or insufficient roasting phenomenon. Water gypsum has high conversion rate and stable quality. When preparing hemihydrate gypsum, the content of anhydrite and dihydrate gypsum is less than 1wt%, and the content of hemihydrate gypsum is greater than or equal to 85wt%.

(3) In the method for comprehensive utilization of gypsum raw materials provided by the present invention, the atmosphere and temperature of the roasting process can be flexibly and timely adjusted by using a control medium.

(4) The method for comprehensive utilization of gypsum raw materials provided by the present invention adopts the roasted tail gas and/or hot gas to preheat the material, and fully recovers the heat of the process.

(5) The method for comprehensive utilization of gypsum raw materials provided by the present invention can be continuously produced, which is convenient for large-scale production.

Description of drawings

1 is a schematic diagram of a device for comprehensive utilization of gypsum raw materials provided in Example 1 of the present invention.

Fig. 2 is the XRD pattern of the phosphogypsum raw material used in Example 1 of the present invention.

3 is a schematic diagram of a device for comprehensive utilization of gypsum raw materials provided in Example 2 of the present invention.

4 is a schematic diagram of a device for comprehensive utilization of gypsum raw materials provided in Example 3 of the present invention.

In the figure: 1-pretreatment unit; 2-preheating unit; 3-fluidized roasting unit; 4-finished product unit; 5-heating unit; 6-dust removal unit.

Detailed ways

The technical solutions of the present invention are further described below with reference to the accompanying drawings and through specific embodiments.

The present invention will be described in further detail below. However, the following examples are only simple examples of the present invention, and do not represent or limit the protection scope of the present invention. The protection scope of the present invention is subject to the claims.

1. Example

Example 1

This embodiment provides a device for comprehensive utilization of gypsum raw materials. As shown in FIG. 1 , the device for comprehensive utilization of gypsum raw materials includes a pretreatment unit 1 , a preheating unit 2 , a fluidized roasting unit 3 and a finished product unit 4 connected in sequence. .

The device for comprehensive utilization of gypsum raw materials further includes a dust removal unit 6 connected to the fluidized roasting unit 3 , and a heating unit 5 connected to the fluidized roasting unit 3 .

The pretreatment unit 1 includes a feed inlet, a regulator inlet and an impurity discharge outlet, and specifically includes a squirrel-cage crusher, a screening and impurity removal device, and a pH adjustment device.

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

The fluidized roasting unit 3 includes a first gas outlet, and the first gas outlet is connected to the preheating unit 2. The fluidized roasting unit 3 includes a control medium inlet. Specifically, the fluidized roasting unit 3 Including bubbling fluidized bed and tempering medium buffer tank, as well as connecting piping and control system between them.

The dedusting unit 6 includes a solid outlet, which is connected to the fluidized roasting unit 3, and the dedusting unit 6 includes a tail gas outlet. Specifically, the dedusting unit 6 includes a bag filter and an induced draft fan connected in sequence. .

The finished product unit 4 includes an additive inlet and a finished product outlet; specifically, the finished product unit 4 includes a batch stirring tank, a metering hopper, a bagging machine and a palletizing robot.

The heating unit 5 is also connected to the preheating unit 2; the heating unit 5 includes an air inlet and a fuel inlet; specifically, the heating unit 5 includes a fan, a fuel tank and a hot blast stove, and the fuel The tank is provided with an air inlet and a fuel inlet.

The preheating unit 2 includes a second gas outlet, and the second gas outlet is connected to the dust removal unit 6. Specifically, the preheating unit 2 is composed of a three-stage cyclone preheater.

The present embodiment also provides a method for comprehensive utilization of gypsum raw materials, the method comprising the following steps:

(1) The phosphogypsum enters the pretreatment unit 1 and is crushed, screened to remove impurities and pH adjusted to obtain a pretreatment material; the pH adjustment is: the phosphogypsum after the screening and removal of impurities is mixed with 2wt% calcium oxide (calcium oxide accounts for The percentage of phosphogypsum quality after sieving and removing impurities) is mixed and adjusted to pH 5 to obtain pretreatment material;

(2) The pretreatment material enters the preheating unit 2 from the screw feeder and is preheated to 90°C. After the water content is less than 10 wt%, it enters the fluidized roasting unit 3, where a control medium is added, and a flow rate of 170°C is carried out by hot gas treatment. State roasting for 60min, remove part of crystal water, obtain hemihydrate gypsum; Described control medium is water vapor;

The temperature of the hot gas is 450°C, and the gas velocity is 5m/s;

The air enters the heating unit 5 from the air inlet and the fuel enters the heating unit 5 from the fuel inlet, and the hot gas generated after combustion enters the preheating unit 2 and the fluidized roasting unit 3 for heating respectively, and the gas generated by the fluidized roasting enters the preheating unit 2 for heating. Preheating, saving energy, the gas generated by the preheating unit 2 enters the dedusting unit 6 and the solid part returns to the fluidized roasting unit 3 after dedusting, and the gas part is discharged in the form of tail gas;

(3) The calcined gypsum described in step (2) enters the finished product unit 4 and is mixed with expanded perlite, cement and quartz sand to obtain light plastering gypsum mortar.

In the present embodiment, the phosphogypsum (XRF composition analysis of phosphogypsum is shown in Table 1, and the XRD phase diagram is shown in Figure 2). As can be seen from Figure 2 and Table 1, the main components in the phosphogypsum are calcium sulfate dihydrate, and the phosphogypsum is Under the control of the tempering medium, hemihydrate gypsum was obtained by roasting at 170 °C. The composition of the hemihydrate gypsum was tested as shown in Table 2. The content of hemihydrate gypsum was 89.3 wt%. No anhydrite was detected. 0.1 wt%. The process of roasting is uniform, the product quality is stable, and there is no over-firing phenomenon; the preheating unit 2 reasonably recycles and utilizes the waste heat of the process, which improves the heat utilization rate; the roasting temperature is flexibly adjusted.

Table 1

name Content (wt%) SO₃ 54.126 CaO 35.083 F 3.531 SiO₂ 2.629 K₂O 2.265 P₂O₅ 0.854 Al₂O₃ 0.759 Fe₂O3 0.475 MgO 0.075 TiO₂ 0.073 SrO 0.072 Na₂O 0.048 MnO 0.008

Example 2

This embodiment provides a device for comprehensive utilization of gypsum raw materials. As shown in FIG. 3 , the device for comprehensive utilization of gypsum raw materials includes a pretreatment unit 1, a preheating unit 2, a fluidized roasting unit 3 and a finished product unit connected in sequence. 4.

The device for comprehensive utilization of gypsum raw materials further includes a dust removal unit 6 connected to the fluidized roasting unit 3 .

The pretreatment unit 1 includes a feed inlet, a conditioner inlet and an impurity discharge outlet, and specifically includes an impact crusher and a screening and impurity removal device.

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

The fluidized roasting unit 3 includes a first gas outlet, and the first gas outlet is connected to the preheating unit 2. The fluidized roasting unit 3 includes a control medium inlet, an air inlet and a fuel inlet. Specifically, the The fluidized roasting unit 3 includes a bubbling fluidized bed with a combustion chamber and a tempering medium buffer tank, as well as a connecting pipeline and a control system therebetween. A control medium inlet is provided on the tempering medium buffer tank. The combustion chamber of the bubbling fluidized bed with combustion chamber is provided with an air inlet and a fuel inlet.

The dedusting unit 6 includes a solid outlet, which is connected to the fluidized roasting unit 3, and the dedusting unit 6 includes a tail gas outlet. Specifically, the dedusting unit 6 includes a first-stage cyclone, Bag filter and induced draft fan.

The finished product unit 4 includes an additive inlet and a finished product outlet; specifically, the finished product unit 4 includes a batch stirring tank, a metering hopper, a bagging machine and a palletizing robot.

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

The present embodiment also provides a method for comprehensive utilization of gypsum raw materials, the method comprising the following steps:

(1) After the layered gypsum ore enters the pretreatment unit 1 and is crushed and screened to remove impurities, the pretreated material is obtained;

(2) The pretreatment material enters the preheating unit 2 from the screw feeder to be preheated to 60°C, and after the water content is less than 10 wt%, it enters the fluidized roasting unit 3, adds the regulating medium, and undergoes hot gas treatment for 140°C flow. State roasting for 120min, remove part of crystal water, obtain hemihydrate gypsum; Described control medium is air;

The temperature of the hot gas is 250°C, and the gas velocity is 2m/s;

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

(3) The hemihydrate gypsum described in step (2) enters the finished product unit 4 and is mixed with expanded perlite, cement and quartz sand to obtain light plastering gypsum mortar.

In this example, the layered gypsum ore is roasted at 140° C. under the control of a tempering medium to obtain hemihydrate gypsum. Its composition is shown in Table 2 after testing, and the content of hemihydrate gypsum is 89.2 wt %. The process of roasting is uniform, and there is no over-firing phenomenon; the preheating unit 2 reasonably recycles and utilizes the waste heat of the process, and improves the utilization rate of heat; the roasting temperature is flexibly adjusted. The fluidized roasting unit 3 has its own combustion chamber, which simplifies the technological process.

Example 3

This embodiment provides a device for comprehensive utilization of gypsum raw materials. As shown in FIG. 4 , the device for comprehensive utilization of gypsum raw materials includes a pretreatment unit 1 , a fluidized roasting unit 3 and a finished product unit 4 connected in sequence.

The device for comprehensive utilization of gypsum raw materials further includes a dust removal unit 6 connected to the fluidized roasting unit 3 , and a heating unit 5 connected to the fluidized roasting unit 3 .

The pretreatment unit 1 includes a feed inlet, a conditioner inlet and an impurity discharge outlet, and specifically includes a cone crusher and a screening and impurity removal device.

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

The fluidized roasting unit 3 includes a first gas outlet, and the first gas outlet is connected to the dust removal unit 6. The fluidized roasting unit 3 includes a control medium inlet. Specifically, the fluidized roasting unit 3 includes Vibrating fluidized bed and tempering medium buffer tank, as well as connecting pipes and control systems between them.

The dedusting unit 6 includes a solid outlet, which is connected to the fluidized roasting unit 3, and the dedusting unit 6 includes a tail gas outlet. Specifically, the dedusting unit 6 includes a 2-stage cyclone, Bag filter and induced draft fan.

The finished product unit 4 includes an additive inlet and a finished product outlet; specifically, the finished product unit 4 includes a batch stirred tank, a metering hopper and a material storage tank.

The heating unit 5 includes an air inlet and a fuel inlet; specifically, the heating unit 5 includes a fan, a coal bunker, a coal-fired boiler and a ceramic filter. The coal-fired boiler is provided with an air inlet, and the coal bunker is provided with an air inlet. A fuel inlet is provided.

The present embodiment also provides a method for comprehensive utilization of gypsum raw materials, the method comprising the following steps:

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

(2) The pretreatment material enters the preheating unit 2 from the screw feeder and is preheated to 70°C. After the water content is less than 10 wt%, it enters the fluidized roasting unit 3, where a control medium is added, and the hot gas treatment is carried out for a flow rate of 150°C. State roasting for 5min, remove part of crystal water, obtain hemihydrate gypsum; Described regulation medium is air;

The temperature of the hot gas is 850°C, and the gas velocity is 10m/s;

The air enters the heating unit 5 from the air inlet and the fuel enters the heating unit 5 from the fuel inlet. After combustion, hot gas is generated and enters the fluidized roasting unit 3 for heating. The gas generated by the fluidized roasting enters the dust removal unit 6 and partially returns to the fluidized roasting after dust removal. Unit 3, part of which is discharged in the form of tail gas;

(3) The hemihydrate gypsum described in step (2) enters the finished product unit 4 and is mixed with expanded perlite, cement and quartz sand to obtain light plastering gypsum mortar.

In this example, the layered gypsum ore is roasted at 150° C. under the control of a temperature-regulating medium to obtain hemihydrate gypsum. After testing, its composition is shown in Table 2, and the content of hemihydrate gypsum is 89.5 wt %. The roasting temperature in the process is flexibly adjusted, the roasting is uniform, and there is no over-firing phenomenon.

Example 4

This embodiment provides a device for comprehensive utilization of gypsum raw materials. The device for comprehensive utilization of gypsum raw materials is the same as that in Embodiment 1 except that "the first gas outlet of the fluidized roasting unit is connected to the dust removal unit".

In this example, phosphogypsum is roasted at 170° C. under the control of a tempering medium to obtain hemihydrate gypsum. The roasting process is uniform, the product quality is stable, and there is no over-firing phenomenon. After testing, its composition is shown in Table 2, and the content of hemihydrate gypsum is 87.6wt%; but compared with Example 1, the fluidized roasting unit The gas directly enters the dust removal unit for dust removal treatment, and the heat utilization rate is worse than that of Example 1, which shows that the present invention preferably connects the first gas outlet with the preheating unit to improve the heat utilization rate.

Example 5

The present embodiment provides a method for comprehensive utilization of gypsum raw materials, and the method adopts the device provided in Embodiment 2 to carry out, and specifically includes the following steps:

(1) After the layered gypsum ore enters the pretreatment unit and is crushed and screened to remove impurities, the pretreatment material is obtained;

(2) The pretreatment material enters the preheating unit from the screw feeder and is preheated to 110°C. After the water content is 8 wt%, it enters the fluidized roasting unit, adds a regulating medium, and undergoes hot gas treatment for fluidization at 120°C. Roasting 180min, removes part of crystal water, obtains hemihydrate gypsum (its composition is as shown in Table 2); Described regulation and control medium is air;

The temperature of the hot gas is 650°C, and the gas velocity is 10m/s;

Air enters the combustion chamber of the fluidized roasting unit from the air inlet and fuel from the fuel inlet. After combustion, hot gas is generated to supply heat for the fluidized roasting. The gas generated by the fluidized roasting enters the preheating unit for preheating, saving energy. The gas generated by the preheating unit enters the dedusting unit and returns to the fluidized roasting unit after dedusting, and part of it is discharged in the form of tail gas;

(3) The hemihydrate gypsum precursor described in step (2) enters the finished product unit and is mixed with expanded perlite, cement and quartz sand to obtain light plastering gypsum mortar.

2. Comparative ratio

Comparative Example 1

This comparative example provides a device for comprehensive utilization of gypsum raw materials. The device for preparing gypsum finished products from gypsum raw materials is the same as that in Example 1, except that the fluidized roasting unit is replaced by a double-cylinder rotary calciner.

The present comparative example also provides a method for comprehensive utilization of gypsum raw materials. The method is the same as in Example 1 except that the calcining in the fluidized calcining unit is replaced by calcining in a double-cylinder rotary calciner.

Since the double-cylinder rotary calciner is used in Comparative Example 1, the flame-throwing furnace is located at one end of the feed port of the calciner, and the flame-spraying direction is toward the open end of the inner cylinder of the calciner, so the high-temperature flue gas is prone to overburning when it contacts the material. , after testing its composition as shown in Table 2, the content of hemihydrate gypsum is 62wt%, compared with Example 1, the product roasting is uneven and the quality is unstable, and the content of hemihydrate gypsum is greatly reduced, thus showing that, The invention improves the stability and quality of hemihydrate gypsum by adopting fluidization technology.

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

Table 2

sample Gypsum dihydrate (wt%) Hemihydrate gypsum (wt%) Anhydrite (wt%) Phosphogypsum 91.07 0 0 Layered gypsum mine 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 comprehensive utilization of gypsum raw materials of the present invention is not limited to the phosphogypsum and layered gypsum ore exemplified in the embodiment, and is limited by space limitations, and is not exemplified in the present invention. It adopts desulfurized gypsum, gypsum mine waste, citric acid gypsum , fluorine gypsum, salt gypsum, monosodium glutamate gypsum, copper gypsum, titanium gypsum, boron gypsum, waste gypsum material, fibrous gypsum ore or waste gypsum mold and other gypsum any one or a combination of at least two can be prepared to obtain high purity Hemihydrate gypsum.

To sum up, the device for comprehensive utilization of gypsum raw materials provided by the present invention adopts a fluidized roasting unit, which has a large reaction area, high reaction rate, uniform heating and small footprint; no excessive or insufficient roasting phenomenon, and uses roasting. The tail gas is discharged after dust removal, and there is no dust pollution; the method for comprehensive utilization of gypsum raw materials provided by the invention can realize the comprehensive utilization of solid waste, reduce the environmental pollution of soil, water and atmosphere caused by the stacking of solid waste, and the product quality is stable, The content of hemihydrate gypsum is greater than or equal to 85 wt %, and the total content of dihydrate gypsum and anhydrite is less than 1 wt %, which has good popularization and application value.

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 rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of the selected components of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims (28)

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:

(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 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;

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

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