2.1 Batch preparation for getting slag melt.
Raw materials are delivered to the plant by road. Raw material is discharged into the receipt bay of open storage, and then it is loaded to the receiving hopper of batch preparation system by shovel loader. From receiving hopper it is conveyed by vibrating feeder and belt conveyer to the batch preparation section, then by reversible belt conveyor it’s distributed to the day hoppers. Day hoppers’ materials are automatically weighed and metered by batch-weighing scales for preparation of batch with determined chemical composition. Materials’ mixing is carried out in the overturning places.
Basic materials for batch preparation:
- blast-furnace slag of metallurgical production;
- fiber forming debris (shot);
- acidating agentin the form ofporphyrite screenings.
After that batch by hoist and system of belt conveyors is loaded to the furnace section and distributed to the 8 service hoppers. Then by special loading devices batch is metered to the furnace for making slag melt.
Batch preparing equipment is not included into the contents of delivery.
2.2 Getting of slag melt.
Regenerative gas bath furnace with melting capacity 4 tonsper hour is used as melting unit. Bath furnace achieves temperature requirement for 1500°C in 15 days approximately and operates continuously during whole operating period till the overhaul repair. Operating period of furnace is 2 years. Bath furnace operatesusing natural gas. For burning of the gas furnace is equipped with 6 gas burners. Feeder with 3 gas burners is used to get the required temperature and viscosity of the melt lava.
For running and controlling of melt lava feeder is equipped with water-cooled panel with melt flow control device.
Bath furnace with its service systems is not included into the contents of delivery.
2.3 Slag melt processing into fiber wool.
Slag melt from the furnace uniformly and in controlled amount with the help of melt lava flow control system flows onto the 4-rolls centrifuge to fiberize it. 80% of melt lava is fiber and 20% is nonfibrous debris (or shot).
Centrifuge is equipped with few service systems:
- Centrifuge rolls cooling system;
- Oil mist lubrication system for spindle bearings;
- Wool blowing off system;
- Binder adding system;
- Centrifuge rolls rotation speed control system.
Achieve optimal fiber wool diameter by changing rolls rotation speed, generally by speed increasing, and by changing parameters of viscosity and temperature.
With the help of centrifuge blow off system and wool collecting machine suction system fiber wool is separated from the debris and is blown to the wool collecting machine; where fiber collects on the perforated surface of the drum forming initial carpet. Thickness of the initial carpet is regulated by wool collecting machine drum rotation speed depending on melt lava production rate and programmed quality of the product resistance strength.
Binder, which is based on synthetic resin and water-repellent, anti-dustand increasingadhesive strength of binder and wool emulsions, is feed automatically to the centrifuge fiber forming zone. Pump through nozzles located on the centrifuge’s frame feeds binder for its uniform spraying on the wool. The amount of spraying binder can be adjusted and regulated by flow rate meters.
Nonfibrous debris (or shots) separate from wool, thencollect on the screw conveyor, which disposes shots to the wastes recycling line for its repeat melting and later use. Fiberization wastes recycling line is not included into the contents of delivery.
2.4 Slag wool carpet forming.
The following equipment is involved in slag wool carpet forming:
- Circular type wool collecting machine;
- Carpet turning device;
- Pendulum wool allocating machine;
- Crimping machine;
- Pressuring machine.
Fiber forming process goes consistently and continuously according to the set-up parameters.
In the circular type wool collecting machine vacuum is created by high power fan (315KW). Wool with binder sprayed on it blown off from the centrifuge, and then drawn to the perforated surface of the rotating drum forming initial carpet. Thickness of initial carpet is regulated by wool collecting chamber drum rotation speed depending on melt lava production rate. Thickness of the initial carpet affects productcompression resistancestrength and must be as low as possible.
Initial slag wool carpet separates from drum surface by air blowing off nozzles, which located inside drum, after that carpet supplied to the belt conveyor of carpet turning device.
Wool collecting machine equipped with drum perforation holes cleaning system, it cleans from stuck wool and binder. This system includes mechanical brush and water cleaning, water is supplied by nozzle under the pressure about 120 bars. Phenolic water is supplied on the filtration and should be used in binder preparation.
Carpet turning device is designed to turn carpet through 90 degrees and allows to place equipment along the center-line in order to save production area. It includes the following:
- Belt conveyor to deliver carpet from wool collecting machine drum to carpet turning device;
- Roller mechanism for carpet turn through 90 degrees;
- Belt conveyor to deliver carpet to the pendulum wool allocating machine.
Pendulum wool allocating machine is a system of parallel belt conveyors, which swinging acrossslate-type receiving conveyor. Slag wool initial carpet is supplied between parallel conveyors and allocated on the slate-type conveyor. Number of wool, needed to produce panel with determined thickness and density parameters, can be regulated by the speed of slate-type receiving conveyor.
Slag wool carpet is delivered to the crimping machine by the system of conveyors (including slate-type conveyor), there carpet is densifiedin the longitudinal and vertical directions. At this time part of the wool locates vertically increasing slag wool products compressionresistance strength. Due to the longitudinal and vertical dencifying different density of end product is excluded.
From crimping machine carpet delivered to pressuring machine, where in order to reduce the load on the curing oven conveyors, carpet is pre-pressed to the thickness which is close to the aimed product thickness and then carpet delivered to the curing oven.
2.5 Thermal treatment and cooling of slag wool carpet.
Curing oven equipped with the hot blast system, at a temperature of 200-250°C synthetic resin is curing and slag wool carpet gets aimed density. Thermal treatment of slag wool carpet is carried out by repeated hot blast through the carpet. Part of furnace gas ejected through filter into the atmosphere. Filter is not included into the contents of delivery.
Curing oven has 4 sections and has 4 hot blast furnaces where natural gas is burned. Each of hot blast furnaces equipped with smoke exhauster, it provides necessary pressure for passage of diluted furnace gas through the carpet.
Thespace between the upper and bottom layer could be adjusted freely according to the aimed thickness of the product.
Carpet cures in curing oven, then in the cooling section itis cooled with cold air. Waste air ejected through filter into the atmosphere.
2.6 Cured carpet cutting into product and its packing.
After cooling in cooling chamber carpet is cutted into products with required dimensions.
Longitudinal cutting blades cut carpet along the line, getting desired width of the product, it also cuts side edges of the carpet.
Cutting scraps of slag wool product milled by special grinding machines and conveyed to the specialized storage silos. While producing low density products milled scraps from silos conveyed to woolcollecting machine on the surface of initial carpet.
Cross cutting blades cut carpet into desired length product.
The automatic stacking machine could pile up and stack the boards in the aimed size technology package.Then this package conveyed by the system of conveyors and turning table to the packing machine.The packing machine is used to pack slag wool boards inpolyethylene thermal shrinking film. Board packages remove by hand from the packing machine roller conveyor, then it puts on the pallets. After pallets with ready product transported by automatic loaders to finished-products storage and then sort goods by consignments.
To storage product at the outdoor area pallets with ready product is additionally filmed.
2.7 Binder making.
Binder is prepared on the special equipment in the binder making zone. Phenol-formaldehyde resin “Prefere” is used, it delivered to the factory by truck tanks. Resin sucked by special pumps to the receiving tanks. Water-repellent, finishing, anti-dust emulsions delivered to the factory in plastic containers volume 1m3.
Desired number of resin, water, water-repellent, finishing, anti-dust emulsions with the help of metering pumps deliver to the mixing tank, where it is mixed thoroughly. Ready binder delivered by pump through flow rate meters to the centrifuge nozzles.
2.8 Production line performance capabilities.
Production line produces slag wool panels and mates with synthetic binder, capacity is about 4,3 tons per hour.
For producing slag wool stitched mates there are special off-line machines for blanket stitching, rolling, cutting and thermal shrinking film packing.
Production line is almost fully automatic and is run by operators with the help of special computer programs.
Production line HEBEI GUANGXING MACHINERI TECHNOLOGY CO., LTD allows to produce wide range of products with different density, thickness and application field.
All the maintenance services like plannedpreventative maintenance, routine maintenance etc. are according to the schedule of line operation and production. While production line scheduled maintenance is held, furnace is non-stop working, operation parameters of the furnace keep the same.