Analysis of grinding production process of building gypsum powder production line
Gypsum powder production line is the natural ore dihydrate gypsum (raw gypsum) or industrial by-product gypsum (FGD gypsum, phosphogypsum, etc.) through the special mill grinding fine and after a certain heating calcining temperature, dehydrating dihydrate gypsum decomposition, get to beta half water gypsum (CaSO4•1/2H2O) as the main ingredients of the product, is the construction gypsum (plaster of Paris).
This is a set of high-yield gypsum powder production technology carefully designed by SMMVIK company on the basis of more than 20 years of experience in the research and development of milling equipment, aiming at the characteristics of gypsum. The technology is dry production, which realizes self-grinding and self-selection. Through the frequency conversion powder separator, the gypsum can be directly ground to meet the GB/T9776-2008 standard of "Gypsum of Construction" without external screening or sorting. At the same time, due to the use of internal circulating air, the gypsum powder that meets the finished product can be quickly blown out, completely avoiding the phenomenon of over-grinding, and greatly improving the output and production efficiency; and the system adopts a dust collector, and the production can meet the national environmental protection requirements.
1. Introduction to the production process
The crusher crushes the large-sized gypsum ore into small particles smaller than 30mm, and transports it to the mill for grinding. The gypsum raw powder that reaches the required fineness of the product after grinding is sent to the boiling furnace for calcination. Parts are returned to the mill for re-grinding until qualified. The qualified gypsum powder after calcination is sent to the clinker silo for storage or sent to the product workshop for use.
2. Process and equipment selection
According to the process requirements, the building gypsum production line is usually divided into five parts, which are crushing system, grinding system, calcining system, material storage and conveying system and electric control system.
01. Crushing system:
The gypsum raw material is evenly and quantitatively fed into the crusher by the feeder, and the crusher crushes the large-sized gypsum ore into small particles less than 30mm. According to the size of gypsum raw materials and different output requirements, crushers of corresponding specifications can be selected. Usually, PE jaw crushers, HP hydraulic cone crushers or PF impact crushers are selected for the crushing process. In order to protect the environment clean, it can be equipped with dust removal equipment to meet the environmental emission requirements.
02. Material conveying:
The crushed gypsum raw material is transported by the elevator to the storage bin for use. The storage bin can be designed according to the requirements of the material storage time to ensure a stable supply of materials. At the same time, each part of the material turnover adopts the hoist to reduce the floor space.
03. Grinding system:
The gypsum raw materials in the storage bin are uniformly and continuously fed into the pulverizer through the vibrating feeder for grinding and finishing. Then, through the combined action of the fan and the analyzer, the gypsum raw powder that meets the fineness requirements is sorted. The material passing through the grinding system is changed from 0 to 30 mm in particle size to 80 to 120 mesh, which meets the fineness requirements of gypsum powder.
The main equipment of the grinding system is: elevator, storage bin, vibrating feeder, pulverizer, screw conveyor, bag filter, etc. The mill equipment adopts the new MTW European-style mill, which has large output and high fineness. Because the European-style mill has a powder selection device inside, it does not need an external powder classifier, which makes the process simple.
04. Calcining system:
The raw powder from the grinding system is transported to the boiling furnace for calcination, and the calcined cooked powder is transported by the elevator to the finished product warehouse for use. The system mainly includes hoist, boiling furnace, electrostatic precipitator, roots blower and other equipment.
So far, the production process of the entire building gypsum powder production line has been completed. The quality of the building gypsum powder processed by this production line is good. Due to the use of a low-temperature heat source, the gypsum is not easy to overburn. As long as the discharge temperature is properly controlled, the finished product does not contain dihydrate gypsum. , Anhydrite is only within 5%, and the rest are hemihydrate gypsum. Such a composition is ideal, and the physical properties are also very stable.
05. Electrical control system:
The electrical control system adopts the current centralized control, DCS control or PLC control, and each control element adopts the products of international famous brands.
3. Technical indicators of gypsum powder products
01. Product quality: meet or exceed the requirements of the national "Building Gypsum" standard (GB9776-2008).
02. Fineness: 80-200 mesh, sieve residue "10%.
03. Flexural strength (directly related to raw materials): ≥1.6Mpa; Compressive strength: ≥3.0Mpa.
04. Main phase composition: Hemihydrate gypsum content: ≥80% adjustable
Dihydrate gypsum content: ﹤5% adjustable
Soluble anhydrite content: <5% adjustable
05. Initial setting time: adjustable from 3 to 8 minutes; final setting time: adjustable from 6 to 15 minutes.
06. Standard thickness: 78～85% adjustable.
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