CN112390556A - Process and device for producing high-strength gypsum by using phosphogypsum - Google Patents
Process and device for producing high-strength gypsum by using phosphogypsum Download PDFInfo
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- CN112390556A CN112390556A CN201910747382.7A CN201910747382A CN112390556A CN 112390556 A CN112390556 A CN 112390556A CN 201910747382 A CN201910747382 A CN 201910747382A CN 112390556 A CN112390556 A CN 112390556A
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B11/00—Calcium sulfate cements
- C04B11/26—Calcium sulfate cements strating from chemical gypsum; starting from phosphogypsum or from waste, e.g. purification products of smoke
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/46—Sulfates
- C01F11/466—Conversion of one form of calcium sulfate to another
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Abstract
A process for continuously producing high-strength gypsum by utilizing solid waste phosphogypsum is suitable for batch production of high-strength gypsum powder and crystal whiskers; the method comprises an acid pickling pretreatment process, a neutralization pretreatment process, a pre-crystal transformation process, a crystal transformation process and a high-temperature drying process, and the high-strength gypsum powder is continuously produced.
Description
Technical Field
The invention belongs to the technical field of solid waste treatment, and particularly relates to a process and a device for producing high-strength gypsum by using phosphogypsum.
Background
Phosphogypsum (pg); preparing 1 ton of phosphoric acid (calculated by 100 percent of P2O 5) to generate 4.8-5.0 ton of phosphogypsum; the organic phosphorus-containing solid waste is offwhite or gray black, wet powder with 10-30% of water is attached, the pH is =1.9-5.3, F < - > is less than 0.5%, the particle diameter is generally 5-50 mu m, the color is offwhite, some of the particles are yellow and gray yellow, the chemical components are complex, and the organic phosphorus, the inorganic phosphorus, the fluoride, the components such as fluorine, potassium, sodium and the like and other inorganic substances are contained, so that the organic phosphorus-containing solid waste is an industrial solid waste; the high-strength gypsum is a high-quality cementing material, is widely applied to the fields of ceramics, precision casting, medical use, aviation, ships, automobiles, plastics, building art, industrial art and the like, is made into various molds and models, is favored due to the superiority of the performance of the high-strength gypsum, and has very large social demand. With the rapid development of economy in recent years, the demand is increasing, and the quality and performance requirements of gypsum are higher and higher.
Disclosure of Invention
In order to overcome the technical problems in the prior art, the invention aims to provide a process for continuously producing high-strength gypsum by using solid waste phosphogypsum, which is suitable for batch production of high-strength gypsum powder and crystal whiskers; the method is characterized by comprising an acid pickling pretreatment process, a neutralization pretreatment process, a pre-crystal transformation process, a crystal transformation process and a high-temperature drying process, and the method is used for continuously producing the high-strength gypsum powder and is characterized in that:
firstly, continuously adding phosphogypsum into an acid-washing pretreatment device, strongly washing under the action of a stirring device and an ultrasonic device, wherein the process conditions are that the sulfuric acid concentration of a washing solution is 1-5%, the solid-liquid ratio of the phosphogypsum to a cleaning solution is 1: 4-1: 2, the washed mixed solution is pumped into a solid-liquid separation device by an acid-washing pump, acid liquor and solid dihydrate gypsum are separated, the acid liquor flows into the acid-washing pretreatment device for recycling, and the solid dihydrate gypsum is input into a neutralization pretreatment device;
secondly, stirring and mixing the dihydrate gypsum subjected to acid-soluble pretreatment in a neutralization pretreatment device, adding lime water to adjust the pH value of the mixed solution, feeding the neutralized mixed solution into a solid-liquid separation device under the action of a neutralization pump, separating out neutralized liquid and solid dihydrate gypsum, allowing the neutralized liquid to flow into the neutralization pretreatment device for recycling, and feeding the solid dihydrate gypsum into a pre-crystal transformation flow after adding a crystal transformation agent in proportion;
thirdly, stirring and mixing the pretreated dihydrate gypsum and the crystal conversion liquid in a crystal pre-conversion device, slowly dehydrating and crystallizing in the crystal conversion liquid at the temperature of 385k plus or minus 5k to generate hemihydrate gypsum crystal nuclei, and transferring the hemihydrate gypsum crystal nuclei, the dihydrate gypsum and the crystal conversion liquid to the crystal conversion flow from the bottom of the crystal pre-conversion device by a delivery pump after the hemihydrate gypsum crystal nuclei grow to reach balance in the crystal conversion liquid;
fourthly, the crystal transformation process is that the crystal nucleus of the semi-hydrated gypsum, the dihydrate gypsum and the crystal transformation liquid are crystallized under the condition of 405k plus or minus 5 k; after high-temperature solid-liquid separation, the crystal transformation liquid returns to the pre-crystal transformation device for recycling, and the semi-hydrated gypsum crystal enters a high-temperature drying device;
fifthly, in the high-temperature drying device, the semi-hydrated gypsum crystals are driven by the stirring blades rotating at high speed under negative pressure to be in contact with the inner cylindrical surface of the dehydration device again, and are discharged to an output device from the bottom after being heated and dried again, the drying temperature is 410k, and the high-strength gypsum products are continuously output at plus or minus 5 k.
The device for continuously producing the high-strength gypsum by using the phosphogypsum is a continuous production line which consists of an acid-washing pretreatment device, a neutralization pretreatment device, a pre-crystal-transformation device, a crystal-transformation device and a drying device in sequence, and is characterized in that vapor which is compressed by a vapor compressor in the drying device and is discharged by the drying device is heated by the pre-crystal-transformation device to generate condensed water, and the condensed water is heated by the pretreatment device and then discharged; the crystal transformation liquid separated by the high-temperature solid-liquid separation device of the crystal transformation device is heated by a feeding pipe of the crystal transformation device and then flows back to the pre-crystal transformation device; the cooling oil of the output pipe of the screw conveyer heats the feed pipe of the pretreatment device through the connecting pipeline.
The acid pickling pretreatment device neutralization pretreatment device comprises a cleaning tank body, an ultrasonic generator, a solid-liquid separation device, a spiral stirrer, a cleaning pump and a connecting pipeline, and is characterized in that: a plurality of ultrasonic generators are arranged in the cleaning tank body along the upper part of a bus, and a cooler consisting of spiral half pipes is arranged outside the tank body; the motor part of the spiral stirrer is arranged on the upper part of the cleaning tank and is coincided with the axis of the cleaning tank, the spiral stirring part is arranged in the cleaning tank, one side of the spiral stirrer is provided with a solid-liquid separator, and the other side of the spiral stirrer is provided with a feeding port.
The pre-crystal-transformation device consists of a tank body, a stirring device, a temperature sensor, a pressure sensor, a charging pipe, an output pipe and a connecting pipeline, and is characterized in that the charging pipe is provided with a heating jacket and a heat-insulating layer, the jacket is provided with a liquid inlet and a liquid outlet, the tank body is provided with a steam heating layer and a heat-insulating layer, steam in the heating layer is provided with a steam inlet, a condensate water outlet, the bottom of the condensate water outlet is provided with the heat-insulating layer and the output port; the tank top is respectively provided with a driving motor and a speed reducer of the stirring device, a mechanical seal, a temperature sensor, a pressure sensor and a safety valve.
The crystal transformation device consists of a tank body, a stirring device, a temperature sensor, a pressure sensor, a safety valve, a feeding pipe, an output pipe and a connecting pipeline, and is characterized in that the feeding pipe is provided with a heating jacket and a heat preservation layer, the jacket is provided with a liquid inlet and a liquid outlet, the tank body is provided with an air heat preservation layer and is provided with a communicating port with the atmosphere, the bottom of the tank body is provided with the heat preservation layer and the output port, and a spiral electromagnetic heating coil is arranged outside the; the tank top is respectively provided with a stirring device driving motor, a speed reducer, a mechanical seal, a temperature sensor, a pressure sensor and a safety valve.
The drying device consists of an evaporation tank body, a stirring device, a steam pipeline, a steam compressor, an oil circulating pump and a spiral conveyer; the bottom of the evaporation tank body is provided with a heat insulation layer and an output port, and an electromagnetic heating coil is arranged outside the heat insulation layer; the upper part of the tank body is provided with a feed pipe, the feed pipe is connected with a high-temperature solid-liquid separation device, a feed inlet of the high-temperature solid-liquid separation device is connected with an output regulating valve, and a liquid output port is connected with a crystal liquid reflux pump; the crystal transformation liquid reflux pump is connected with a crystal transformation liquid reflux pipe, and a feed pipe jacket of the crystal transformation device is used for refluxing to the pre-crystal transformation device; the top of the tank body is coaxially provided with a temperature sensor, a pressure sensor and a steam pipeline according to a motor reducer with a stirring device and a sealing device; the steam pipeline is connected with the input port of the steam compressor, and the outlet of the steam compressor is connected with the steam port of the pre-crystal-transformation device through a pipeline; the output pipe of the screw conveyer is additionally provided with a cooling jacket with a spiral oil duct, a cooling oil inlet and a cooling outlet, the cooling oil inlet is connected with the inlet of the cooling circulating pump and the inlet and the outlet of the feeding pipe jacket of the pre-rotating crystal device through pipelines, and the outlet of the cooling circulating pump and the outlet of the cooling liquid are connected into a closed loop oil circuit for forced circulation.
Description of the drawings: description figure 1 is a schematic process flow diagram and figure 2 is a schematic process unit structure diagram.
The process and apparatus structure of the present invention will be further described with reference to fig. 2 and the specific embodiments.
In the first embodiment, high-strength gypsum powder is produced, phosphogypsum is slowly and continuously added into an acid-washing pretreatment device 1 at a speed of 16 kg/min, and is strongly acid-washed under the action of a stirring device 1-7 and an ultrasonic generator 1-3 under the process conditions that the sulfuric acid concentration of a cleaning solution is 1-5%, and the solid-to-liquid ratio of the phosphogypsum to the cleaning solution is 1: 4-1: 2. The mixed liquid after cleaning is input into a solid-liquid separation device 1-5 by an acid cleaning pump 1-4, and acid liquor and solid dihydrate gypsum are separated. The acid liquor flows into the pickling pretreatment device 1 for recycling, and the solid dihydrate gypsum is input into the neutralization pretreatment device 2.
Stirring and mixing the dihydrate gypsum in the neutralization pretreatment device 2, adjusting the pH value of the mixed solution to be 4.5-6 by adding lime water, feeding the mixed solution into a solid-liquid separation device 2-4 through a connecting pipeline under the action of a neutralization pump 2-3, and separating a neutralization solution and solid dihydrate gypsum. The gypsum is fed into the neutralization pretreatment device 2 for recycling, the solid dihydrate gypsum is added with the crystal transformation agent in proportion, passes through the feeding and managing pipe 3-1, is heated by the jacket 3-11 and then enters the pre-crystal transformation device 3.
Stirring and mixing the crystal transformation liquid in the pre-crystal transformation tank body 3-3 and dihydrate gypsum, slowly dehydrating and crystallizing in the crystal transformation liquid with the temperature of 408k plus or minus 5k to generate semi-hydrated gypsum crystal nuclei, heating the mixed liquid by steam, pressurizing the steam discharged by the drying device 5 by a 5-6 steam pipe and a 5-7 steam compressor, then entering the tank body heating layer 3-3 through a steam pipe connector 3-3-1, and discharging condensed water after passing through a condensed water pipe 3-3-2, a semicircular spiral coil 2-1-1 and a spiral coil 1-9. The electromagnetic heating coils 3-9 are automatically electrified for use only when no steam exists or steam heat energy is insufficient, and the hemihydrate gypsum crystal nucleus grows in the crystal transformation liquid and slowly sinks to the bottom to reach balance. The output pumps 3-7 pump the hemihydrate gypsum, the crystal nucleus and the crystal transformation liquid into the crystal transformation device 4 from the bottom of the pre-crystal transformation device.
Crystal nuclei in the crystal transformation device 4 generate semi-hydrated gypsum crystals in crystal transformation liquid with the temperature of 408k plus or minus 5k, the temperature of the crystal transformation liquid is electrified and controlled by a heating coil 4-5, and the semi-hydrated gypsum crystal nuclei grow in the crystal transformation liquid to become semi-hydrated gypsum crystals and slowly sink to the bottom; enters a high-temperature solid-liquid separation device 4-9 through an output adjusting valve 4-7; the separated crystal transformation liquid passes through a crystal transformation liquid reflux pump 4-8, passes through a conveying pipe jacket 4-10 and then returns to the pre-crystal transformation device through a return pipe 3-5 for recycling, and the semi-hydrated gypsum crystals enter a high-temperature drying device 5.
In the high-temperature drying device 5, the semi-hydrated gypsum crystals are driven by the stirring blade rotating at a high speed to contact with the inner cylindrical surface of the high-temperature drying device tank body, are heated and dried again, and are discharged to the output device 5-4 from the bottom. The electromagnetic heating coil 5-3 heats the high-temperature drying device 5, the drying temperature is ensured to be 405k to 410k, the high-temperature potential of the semi-hydrated gypsum product is exchanged in the output device 5-4 to heat the heat conducting oil in the jacket, and then the semi-hydrated gypsum powder product is continuously output from the output port after being cooled. The heat conducting oil enters the jacketed pipe 3-11 of the charging pipe 3-1 through the cooling circulating pump 5-5 and the hot oil pipe 5-8, and then returns to the output device 5-4 through the cold oil pipe 5-9.
Steam discharged by the high-temperature drying device 5 enters a steam compressor 5-7 from a steam pipe 5-6, the temperature is increased by 15k-30k after the steam is compressed, the steam enters a tank body heating layer 3-3 of the pre-crystal-rotating device 3, heat energy of the steam is absorbed by the pre-crystal-rotating device to form condensed water, and the condensed water is re-cooled by a spiral semicircular coil pipe 1-9 of the pre-treatment device and then is discharged at normal temperature through a discharge port 1-10.
And in the second embodiment, gypsum whiskers are produced, the pH value of neutralization pretreatment is adjusted to be in the range of 8.5 to 10, the calcium sulfate whisker crystal transfer agent is replaced, the crystal nucleus in the crystal transfer device 4 is kept unchanged at the temperature of 408k plus or minus 5k according to the production flow in the first embodiment, and the pressure is increased, so that the calcium sulfate whiskers can be produced.
Claims (6)
1. A process for continuously producing high-strength gypsum by using phosphogypsum comprises an acid-washing pretreatment process, a neutralization pretreatment process, a pre-crystal transformation process, a crystal transformation process and a high-temperature drying process, and is characterized in that the process comprises the following steps:
continuously adding phosphogypsum into an acid-washing pretreatment device, strongly washing under the action of a stirring device and an ultrasonic device, wherein the process conditions are that the sulfuric acid concentration of a washing solution is 1-5%, the solid-liquid ratio of the phosphogypsum to a cleaning solution is 1: 4-1: 2, a washing pump pumps the mixed solution into a solid-liquid separation device to separate acid solution and solid dihydrate gypsum, the acid solution flows into the acid-washing pretreatment device for recycling, and the solid dihydrate gypsum is input into a neutralization pretreatment device; stirring and mixing the dihydrate gypsum after acid-soluble pretreatment in a neutralization pretreatment device, adjusting the pH value of the mixed solution by adding lime water, feeding the neutralized mixed solution into a solid-liquid separation device under the action of a neutralization pump, separating out neutralized liquid and solid dihydrate gypsum, enabling the neutralized liquid to automatically flow into the neutralization pretreatment device for recycling, and feeding the solid dihydrate gypsum into a pre-crystal conversion process after adding a crystal conversion agent in proportion; stirring and mixing the pretreated dihydrate gypsum and the crystal transformation liquid in a pre-crystal transformation device, slowly dehydrating and crystallizing in the crystal transformation liquid with the temperature of 385k plus or minus 5k to generate hemihydrate gypsum crystal nuclei, enabling the hemihydrate gypsum crystal nuclei to grow in the crystal transformation liquid to reach balance, and transferring the hemihydrate gypsum crystal nuclei, the dihydrate gypsum and the crystal transformation liquid to a crystal transformation process from the bottom of the pre-crystal transformation device by a delivery pump; the semi-hydrated gypsum crystal nucleus, the dihydrate gypsum and the crystal transformation liquid are crystallized under the condition of 405k plus or minus 5 k; after high-temperature solid-liquid separation, the crystal transformation liquid returns to the pre-crystal transformation device for recycling, and the semi-hydrated gypsum crystal enters a high-temperature drying device; in the high-temperature drying device, the semi-hydrated gypsum crystals are driven by the stirring blades rotating at high speed under negative pressure to contact with the inner cylindrical surface of the dehydration device, are heated and dried again, and are discharged to the output device from the bottom, and the high-strength gypsum products are continuously output at the drying temperature of 410k plus or minus 5 k.
2. A device for continuously producing high-strength gypsum by using phosphogypsum is a continuous production line which is sequentially composed of an acid pickling pretreatment device, a neutralization pretreatment device, a pre-crystal transformation device, a crystal transformation device and a drying device, and is characterized in that vapor which is compressed by a vapor compressor in the drying device and is discharged by the drying device is heated by the pre-crystal transformation device to generate condensed water, and the condensed water is heated by the pretreatment device and then discharged; the crystal transformation liquid separated by the high-temperature solid-liquid separation device of the crystal transformation device is heated by a feeding pipe of the crystal transformation device and then flows back to the pre-crystal transformation device; the cooling liquid of the output pipe of the screw conveyer heats the feed pipe of the pretreatment device through the connecting pipeline.
3. The acid pickling pretreatment device neutralization pretreatment device of claim 2, which consists of a cleaning tank, an ultrasonic generator, a solid-liquid separation device, a spiral stirrer, a cleaning pump and a connecting pipeline, and is characterized in that: a plurality of ultrasonic generators are arranged in the cleaning tank body along the upper part of a bus, and a cooler consisting of spiral half pipes is arranged outside the tank body; the motor part of the spiral stirrer is arranged on the upper part of the cleaning tank and is coincided with the axis of the cleaning tank, the spiral stirring part is arranged in the cleaning tank, one side of the spiral stirrer is provided with a solid-liquid separator, and the other side of the spiral stirrer is provided with a feeding port.
4. The pre-crystallization device according to claim 2, which comprises a tank body, a stirring device, a temperature sensor, a pressure sensor, a feeding pipe, an output pipe and a connecting pipeline, and is characterized in that the feeding pipe is provided with a heating jacket and a heat-insulating layer, the jacket is provided with a liquid inlet and a liquid outlet, the tank body is provided with a steam heating layer and a heat-insulating layer, steam in the heating layer is provided with a steam inlet, a condensate water outlet, the bottom of the tank body is provided with the heat-insulating layer and the output port, and a spiral; the tank top is respectively provided with a driving motor and a speed reducer of the stirring device, a mechanical seal, a temperature sensor, a pressure sensor and a safety valve.
5. The crystal transformation device as claimed in claim 2, which comprises a tank body, a stirring device, a temperature sensor, a pressure sensor, a safety valve, a feeding pipe, an output pipe and a connecting pipeline, wherein the feeding pipe is provided with a heating jacket and a heat-insulating layer, the jacket is provided with a liquid inlet and a liquid outlet, the tank body is provided with an air heat-insulating layer and is provided with a communicating port with the atmosphere, the bottom of the tank body is provided with the heat-insulating layer and the output port, and a spiral electromagnetic heating coil is arranged outside the heat; the tank top is respectively provided with a stirring device driving motor, a speed reducer, a mechanical seal, a temperature sensor, a pressure sensor and a safety valve.
6. The drying device according to claim 2, which is composed of an evaporation tank, a stirring device, a steam pipeline, a steam compressor, an oil circulating pump and a screw conveyer; the bottom of the evaporation tank body is provided with a heat insulation layer and an output port, and an electromagnetic heating coil is arranged outside the heat insulation layer; the upper part of the tank body is provided with a feed pipe, the feed pipe is connected with a high-temperature solid-liquid separation device, a feed inlet of the high-temperature solid-liquid separation device is connected with an output regulating valve, and a liquid output port is connected with a crystal liquid reflux pump; the crystal transformation liquid reflux pump is connected with a crystal transformation liquid reflux pipe, and a feed pipe jacket of the crystal transformation device is used for refluxing to the pre-crystal transformation device; the top of the tank body is coaxially provided with a temperature sensor, a pressure sensor and a steam pipeline according to a motor reducer with a stirring device and a sealing device; the steam pipeline is connected with the input port of the steam compressor, and the outlet of the steam compressor is connected with the steam port of the pre-crystal-transformation device through a pipeline; the output pipe of the screw conveyer is additionally provided with a cooling jacket with a spiral oil duct, a cooling oil inlet and a cooling outlet, the cooling oil inlet is connected with the inlet of a cooling circulating pump and the inlet and the outlet of a feeding pipe jacket of the pre-rotating crystal device through pipelines, and the outlet of the cooling circulating pump and the outlet of cooling liquid are connected into a closed loop oil circuit for forced circulation.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114210693A (en) * | 2021-12-23 | 2022-03-22 | 贵州蓝图新材料股份有限公司 | Deep purification treatment process for chemical waste residues |
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- 2019-08-14 CN CN201910747382.7A patent/CN112390556A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114210693A (en) * | 2021-12-23 | 2022-03-22 | 贵州蓝图新材料股份有限公司 | Deep purification treatment process for chemical waste residues |
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