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Production Technology Description

Cement production technology description

Raw materials for cement production are chalk, clay and pyrites.

Chalk is extracted in "Kamenka" quarry. Stripping operations are executed for chalk extraction preparation by means of walking excavators (1), removal is loaded in dump trucks and transported to the used quarry. Chalk is extracted by means of two walking excavations (2), loaded in dump trucks (3) and after weighing on the weighbridge (4) transported to wash mills (5) (4 wash mills with diameter equal to 12 m). Technical lignosulfonates are added to the wash mills for chalk slurry moisture reduction and flow ability improvement. After the wash mills the chalk slurry is transported to two vertical slurry tanks (6) with the capacity equal to 800 m3 each for further homogenization, accumulation and interim storage. From "Kamenka" quarry the chalk slurry is transported to the industrial site by hydrotransport (3 pump stations) (7).

For the chalk slurry intake, storage and stocking two horizontal slurry tanks № 3, 4 (8) with the capacity equal to 6000 m3 each are used in raw materials workshop. From the horizontal slurry tanks the chalk slurry is transported by pumps to four wash mills (11) for washing with clay and pyrites. From the stockpile clay and pyrites are transported by dumpcars (9) or bucket crane (10) to the feed hopper of the wash mills. After the wash mills the slurry is transported for regrinding to two 3 x 8,5 m slurry mills (12). Horizontal slurry tank №2 (13) with capacity equal to 6000 m3 is used for raw meal storing and pre-mixing. Six vertical slurry tanks with the capacity equal to 800 m3 each are used for slurry mixing according to preset chemical composition. Finished slurry from the vertical slurry tanks is transported to horizontal slurry tank №1 (15) with the capacity equal to 6000 m3. The horizontal slurry tank is used for finished slurry accumulation, homogenization and feeding to burning.

The slurry is transported through the slurry feeder (16) by centrifugal pumps to 4,5 x 5,0 x 170 m rotary kilns (17) for burning. As a result of burning a semi-finished product (clinker) is produced. After rotary kilns clinker is cooled in grate coolers (18) and then it is transported to a hammer crusher (19) for crushing. Then clinker is transported by clinker conveyers (20) to a clinker depot for storage (21).

By means of a bucket crane clinker is transported to the cement mills bins (24) for grinding. Five 3 x 14 m cement mills and one 3,2-14 m cement mill are used for cement grinding. Gypsum rock is added to the cement mills bins for setting time control. When producing portland cement with mineral additives, granulated blast furnace slag and limestone are used as additives. It is possible to add sand from grinding screening up to 5%. Additives are transported to the stockpile by dump cars.

After the cement mills cement is produced by cement-handling air pumps to cement silos (25) for storage and shipment. From the cement silos cement is delivered for slate production, loaded to railway cars or to motor vehicles. There are two packing machines for cement packing in paper bags (25 and 50 kg per bag) and there is also one line for cement packing in polypropylene big bags (1000 kg per bag).

Description of asbestos-cement sheets production technology

Raw materials for asbestos-cement sheets production are cement of own production and asbestos. The enterprise receives asbestos grades A 6-65, A 5-50, A 6-45 from such deposits as Kiembaevskoe, Dzhetygarinskoe and Bazhenovskoe. Incoming in railcars asbestos is palletized in dry roofed store buildings separately according to grades and deposits.

From the store buildings bagged asbestos is transported by forklift trucks for proportioning. Asbestos is proportioned according to the mixture prepared from different grades of asbestos available from the store buildings. The asbestos mixture is transported to a conveyor for asbestos distribution to the edge-runner mills equipped with plate divertors. Then the asbestos mixture is conveyed to one of the edge-runner mills by the conveyor for asbestos distribution. Asbestos is pressed down in the edge-runner mills. Tap water is added from a measuring box into the edge-runner mills. After asbestos has been pressed in the edge-runner mills, it is poured into the asbestos hydro-splitting device where asbestos is finally crushed. Water to the asbestos hydro-splitting device is pumped from the conical part of a clarified (clean) water recuperator.

After asbestos has been crushed in the hydro-splitting device, an asbestos suspension is pumped into a turbomixer where an asbestos-cement mixture is prepared. Cement from a feed bin is conveyed to a weighing batcher by a screw feeder. The weighed cement batch is conveyed to the turbomixer by a screw conveyor. There the asbestos suspension is mixed with cement. Ready asbestos-cement mixture is pumped to a bucket mixture, then to the net-shaped cylinders’ tanks of the sheet-forming machine. Before the asbestos-cement mixture is conveyed to the sheet-forming machine, it is diluted with water pumping from the bottom of a muddy water recuperator.

Filtered water is pumped to the muddy water recuperator. There it is clarified and conveyed to a clean water recuperator. The recuperators of muddy and clean water are regularly blown through.

An elementary film layer formed in the sheet-forming machine is cut from a format drum with an automatic cutting machine and then it is conveyed to the elementary film layer cutting table. The cutting machine disk cutters cut the film layer to the desired length blanks.

Then these blanks are conveyed to the chain corrugating machine where sheets are corrugated. Longitudinal sheets edges are cut with the disk cutters. Cutting waste (as the result of film layers cutting to the desired size) and rejected freshly-formed sheets are conveyed to the cutting waste mixer. Corrugated sheets are conveyed to the stacker table. Then the sheets are transferred to the trolleys of a conveyer for hardening. After preliminary hardening in the conveyer the sheets are unloaded from the trolleys to a humidifying machine by a pile lifter. The sheets are water saturated in the humidifying machine. The sorting unit vacuum box disassembles and stacks sheets (100 sheets per stack). The stacks are packed in metal frames and transported by cranes to the store building for final hardening. After being tested by the Quality Control Department the asbestos-cement sheets are dispatched to customers.

PRUE “Krichevcementnoshifer” produces asbestos-cement corrugated sheets 40\150-8 СТБ1118-98 and asbestos-cement flat unpressed sheets, thickness 6,8,10mm.