The Flow Chart of Natural Gypsum Powder Production Line
Jaw Crusher→Hammer Crusher→Lifter→Material Silo→Measuring Pump→Mill→Selecting Power Machine→Lifter→Raw Material Silo→Screw Feeder→Calciner(Fluidized Bed Furnace)→Electrostatic Cleaning→Cooling→Lifter→Finished Material Silo
Brife Introduction of The Production Craft
The gypsum stone is crushed into granule less than 25mm with crusher. It's stored in raw material silo, then conveyed into grinding mill to make gypsum powder. The powder is classified through a classifier. The qualified powder in required fineness shall be carried to the calciner, while the unqualified powder shall be returned to the grinding mill for further process. The calcined gypsum powder (it's usually called Plaster of Paris) shall be stored in the finished product silo for preparation of plasterboard raw material.
1. Crushing Process
The diameter of gypsum lump should less than 300mm, we use bucket lift truck or manpower transport gypsum lump into jaw crusher, stone crusher gypsum plaster stone, less than 50mm, the bucket elevator and screw conveyor into the grinder bin.
2. Grinding Powder Process
The gypsum materials from crushing process, they will be conveyed into mill silo through bucket elevator and screw conveyor. These gypsum materials will be evenly feed into mill via vibrating feeder,the small size gypsum materials will become to gypsum powder due to the grinding effect, gypsum powder will go out of mill with wind, and will be chosen by powder separatorwhich is on the top of mill, the qualified fineness of powder are separated from the top of mill, other unqualified powder will return into mill for grinding again. The qualified powder through cyclone dust collectorand bag-type splitter will gather into screw convey, and then bucket elevator & screw conveyor transport gypsum powder to calcinationprocess, the surplus powder will be storage into raw material silo through screw conveyor.
3. Calcination Process
The powder materials which are from grinding powder process or powder silo, they will through vertical, horizontal conveyor and then through measuring screw conveyor into boiling furnace for calcination. Boiling furnace take high temperature heat transfer oil as heat source, high temperature heat transfer oil is provided by coal-fired thermal oil boiler. When the high temperature transfer oil enter boiling furnace, its heat will transmit to gypsum powder by heat exchanger, and make CaSO4 *2H2O become into CaSO4 *1/2H2O (building gypsum). During calcination, we adjust discharge temperature according to raw gypsum's feeding quantity, calcined building gypsum continuous automatic discharge from boiling furnace, and are conveyed to building gypsum silo pass through screw conveyor and bucket elevator. And the heat transfer oil will return flow into coal-fired thermal oil boiler for reheat.
4. Batching, packing process
The gypsum is sent to the packing silo through bucket elevator and screw conveyor.
Chemical additives and other raw materials were sent to the batch bin through the electric hoist.
The batching in all the stocks uses the metering screw conveyor which adjusts speed by using inverter and finishes feeding by step less speed.
During production, it will input set formula to the host computer according to the varieties and specifications. Based on the formulation requirements, large amount of construction gypsum was added to the mixer after measured by measurement scale number 1, small amount of materials were added to the mixer after measured by measurement scale number 2. The measurement scale in this project uses dosage method.
The materials will unload to the middle silo after mixing in the mixer.
The building gypsum after mixing is packaged by packing machine (adopt automatic sealing bag), and then delivered into finished product library. The packing machine adopts feedback signal of pressure sensor for controlling the charging of screw feeder. The packing machine will stop to load materials when the weight of materials reaches set value. Next the pounding machine will reshape it as standard shape. Finally the computer-controlled inkjet printing machine will print automatically on the surface of bag which includes date of manufacture, manufacturer, trademark, etc.
The related parameter of the product (GB9776-88 calcined gypsum)
1. Fineness:≥80 mesh
2. Antiflex strength (it is related to the raw material): ≥1.8Mpa; compression strength: ≥3.0Mpa
3. Main component:
semi-hydrated gypsum content: ≥80% adjustable
dehydrate gypsum content: <5% adjustable
Soluble anhydrous gypsum: <5% adjustable
4. The initial setting time: 3~8min adjustable;
The final setting time: 6~15min adjustable
5. Standard consistency: 78~85% adjustable