Gypsum powder is one of the five major gel materials, which is processed through crushing, grinding and other processes. It is widely used in construction, building materials, industrial molds and art models, chemical industry and agriculture, food processing, medicine and beauty and other applications. It is an important industrial raw material.
Gypsum has good sound insulation, thermal insulation, and fire resistance characteristics. In China, natural gypsum reserves are abundant and have been used for a long time. With the improvement of economic and technological levels, gypsum powder production equipment and processes also have more choices and more scientific configuration plans.
White and colorless transparent crystals are usually referred to as transparent gypsum, and sometimes they become gray, light yellow, light brown, and other colors due to impurities.
How do you manufacture gypsum powder? In order to ensure the quality and quantity of gypsum powder in production, many factories have chosen gypsum powder production lines that can be intelligently and automatically completed. From the different application fields of gypsum powder, the gypsum powder production line is mainly divided into construction gypsum production line and desulfurization gypsum production line.
Gypsum powder-making process
According to the process requirements, the construction gypsum production line is usually divided into five parts, including crushing system, storage conveying system, grinding system, calcining system, and electric control system.
STEP1. crushing system
The size and specifications of gypsum ores are different after mining, and the applicable crushing equipment is selected for preliminary crushing treatment according to the actual situation, and the particles with particle size not greater than 35mm are broken.
STEP2. storage conveying system
The crushed gypsum raw material is transported to the storage bin by the elevator. The storage bin is designed according to the requirements of the material storage time to ensure the stable supply of materials. At the same time, all parts of the material turnover are using lifts to reduce the floor area.
STEP3. grinding system
- The grinding process is the core process of gypsum powder production. The gypsum raw material in the storage bin enters the grinding machine through the vibration feeder for finishing. The electromagnetic vibration feeder is set under the storage bin, which is interlocked with the mill to adjust the supply of materials in time according to the running condition of the mill.
- The material is uniformly and continuously fed into the mill by the electromagnetic vibration feeder for grinding.
- The pulverized gypsum powder is blown out by the air flow from the mill blower and graded by the analytical machine above the main engine. The powder with the fineness meeting the specifications enters the large cyclone collector with the air flow, and is discharged as the finished product through the powder outlet pipe after collection.
- The finished product falls into the screw conveyor and is transported to the next system for calcining. The air flow flows from the return duct of the cyclone collector into the blower. The whole air path system is closed circulation and flows under negative pressure. Due to the water contained in the ground raw materials and the evaporation into gas during the grinding process, resulting in an increase in the air volume in the circulating air path, the increased air volume is introduced from the pipe between the large cyclone collector and the blower to the bag dust collector, and then discharged into the environment to ensure that the environment is clean.
- The particle size of the material through the grinding system is changed from 0-30mm to 80-120 mesh, which meets the requirements of the fineness of gypsum powder.
STEP4. calcining system
After grinding is completed, the pulverized gypsum powder is sent to the rotary kiln for calcining by the powder separator, the plaster of Paris is sent to the storage storage by the elevator, and the materials that do not meet the requirements are continued to be returned to the mill for grinding; The system mainly includes lifting machine, boiling furnace, electrostatic dust removal, Roots fan and other equipment.
STEP5. calcining system
The electrical control system adopts the current advanced centralized control, DCS control or PLC control, and the control components are selected international well-known brand products
gypsum powder making machine
Crushing System: jaw crusher and impact crusher
jaw crusher has feed particle size of ≤ 1200mm, a discharge particle size is 10-350mm, and the production capacity can reach 1-1000t/h. Suitable for coarse crushing of large gypsum blocks, with strong crushing ability and high crushing ratio; Impact crusher feed particle size ≤1300mm, production capacity in 30-2000t/h, suitable for small hardness, Mohs hardness of 2 grade gypsum for fine crushing processing, and the discharge particle type is very good, uniform particle size.
Grinding System: Raymond mill, bucket elevator and vibrating feeder.
The grinding process of gypsum generally selects Raymond mill for processing operations. Raymond mill is good at high fineness grinding of non-flammable and explosive materials with Mohs hardness not greater than 9.3 and humidity below 6%. The feed particle size of Raymond mill is ≤25-≤30㎜, the discharge particle size is 0.044-0.173㎜, and the class production is about 8-176t.
Calcination System: Rotary kiln
Rotary kiln and related equipment is used in calcination section of gypsum powder production line.
Gypsum powder production line main technical parameters
| Annual production (tons) | 50000 | 100,000 | 150,000 | 200,000 | 250,000 | 300,000 | 400,000 | 50,0000 |
| Main equipment | Specifications | |||||||
| Gypsum rotary kiln | Ø2.0×24m | Ø2.4×24m | Ø2.8×26m | Ø3.0×26m | Ø3.2×26m | Ø3.4×28m | Ø3.6×28m | Ø4.0×28m |
| Baghouse dust collector | PPC96-6 | PPC96-8 | PPC128-6 | PPC128-9 | PPC96-2×9 | PPC128-2×7 | PPC128-2×9 | PPC128-2×12 |
| Raw material | Dihydrate desulfurized gypsum (dry base) ≥90%, attached water content ≤15%, water-soluble magnesium oxide (dry base) ≤0.5%, PH value 6-8, chloride ion content (dry base) ≤500mg/kg | |||||||
| calcination temperature(℃) | 150 | |||||||
| Steam consumption index（kd/t gypsum powder） | 500±50 | |||||||
| Power consumption（kw•h/tgypsum powder） | 25±5 | |||||||
| Desulfurized gypsum: gypsum powder | 1.4：1 | |||||||
| Setting time | Initial setting ≥8min, final setting ≤30min | |||||||
| Fineness | ≤5% | |||||||
| Strength（MPa） | 2 hours bending resistance ≥3.0MPa, compressive strength ≥6.5MPa; | |||||||
| Three-phase control | Dihydrous gypsum is less than 3%, semi-hydrous gypsum is more than 84%, soluble anhydrous gypsum is less than 3%; | |||||||
| Emission concentration（mg/m3） | ≤30 | |||||||
| Annual working days | ≥300 | |||||||
| Overhaul period(year) | 3 | |||||||
| Heat source or fuel | steam, natural gas, pulverized coal | |||||||
