Equipment for recycling metallurgical wastes
The Samara Strommashina plant has been designing and creating the industrial equipment for over 70 years already. In the latest decades our engineering department is focused on eco trend, implementing new recycling technologies which allow reducing the amount of industrial waste. We offer you the equipment which can recycle slags and by-products into valuable products, for example, construction materials. One of such marketable products is mineral wool.
Slags (ferrous and non-ferrous industry wastes), industrial wastes, such as scrap ceramic bricks, burnt rocks, cement and LECA production waste dust are used as raw materials for mineral wool production.
Blast-furnace slags are the most common raw material for production of mineral wool and products based on it – they are used in solid form, as crushed stone and in flaming form. The crushed stone based on blast-furnace slag for production of mineral wool (GOST 188 66) is used for melting in cupola furnaces, flaming slags – in slag receiving bath-type furnaces. Depending on acidity modulus Ma, crushed stone is classified into category A – with Ma 1.2 and more and category B – with Ma less than 1.2. Depending on grain size, crushed stone is classified into 40 to 70 mm size group and 70 to 120 mm size group.
To correct their chemical composition, sedimentary carbonate rocks are used: limestone, dolomite:
The main index determining suitability of the raw material for mineral wool production is acidity index Ia which is the ratio of the summarised percentage of acid oxides – silicon dioxide SiO2 and aluminium oxide Al2O3 to summarised percentage of the main oxides – calcium (CaO) and magnesium (MgO) in the raw material. The acidity index of type A mineral wool is no less than 1.4, types B and C – no less than 1.2 (GOST 4640); for the wool produced from rocks the recommended acidity index is 1.7 to 2.2, basalt fibre – more than 2.2. The prepared components are used to make charge mixture by weight batching of each component using automatic weigher.
Slag melting units
The main type of melting unit for mineral wool production is cupola furnace. The wide use of cupola furnaces is due to high coefficient of utilisation of the heat generated by combusted fuel, greater performance despite small dimensions, simple design, low capital costs and simple maintenance.
A cupola furnace is a vertical kiln consisting of two main parts – crucible part and shaft part. Fuel is burnt and the raw material is melted in the crucible (lower) part. This is where temperature is high, so the crucible part is protected with a water jacket. Above the water jacket the shaft is protected against exposure to high temperatures by fire-clay brick lining.
The air necessary for fuel combustion is fed into the cupola furnace through special devices – tuyeres which are located symmetrically along the cupola furnace circumference in one to three rows at height equal to 0.5 to 0.8 diameter of the cupola furnace from its bottom. Each row contains 8–6 tuyeres, each 60 to 50 mm in diameter. Tuyeres of each row are connected by a common manifold ring (tuyere belt) through which air flows all over the cupola furnace perimeter.
The screened raw materials and coke are fed from the feed bins through weighing batchers using a skip hoist, conveyor or a bucket with opening bottom to a fed door located in the side wall of the cupola furnace. The cupola furnace operating zone height is 4 to 5 cupola furnace diameters.
The cupola furnace is a continuously operating counterflow heat generating unit. The raw material and fuel loaded from above as sandwiched layers descend, and the fuel combustion products generating in the lower part of the cupola furnace – hot gases – ascend, transferring their heat to the upper material layers. Thus, the raw material moving down the cupola furnace heats up and transforms to a melt. The melt is discharged from the cupola furnace through a tap hole which is usually located in the side wall at the height equal to 0.2 to 0.35 diameter of the cupola furnace from the bottom or in the bottom itself. The tap hole diameter is 35 to 80 mm, it depends on the cupola furnace capacity. To stabilise the melt jet, a forehearth may be integrated to the side tap hole.
The SMT-208 cupola furnaces manufactured by the Strommashina comply with up-to-date environmental requirements. They are completed with CO post-combustion equipment, dedusting unit and evaporating cooling system.
Our plant's specialists can give qualified answers to all questions concerning the technology of production of mineral wool from industrial wastes. Transforming waste materials to valuable products using our equipment, your enterprise not only makes profit, but also preserves cleanliness of the ecosystem.