Equipment and technologies for production of heat insulating construction materials
The construction materials market is one of the most fast-growing segments of the global economy. The heat insulators based on mineral wool are in great demand which is even higher in the construction works season. To increase the production output to the required level, reliable equipment designed for high loads shall be used. Such mineral wool production equipment for sale is offered by the Samara Strommashina plant.
Silicate melts used for production of mineral wool and heat and sound insulating materials based on it are produced in cupola furnaces, gas bath-type kilns, gas-electric and electric kilns. The melting unit type is determined by types of mineral raw materials and power fuel used in the process.
The most common melting unit in the mineral wool production is cupola furnace. Solid lump mineral raw material and foundry coke are used for melting in the cupola furnace.
Technologies for production of heat insulating construction materials
Production of mineral wool and products based on it include such basic processes as preparation of raw materials, raw mixture (charge) compounding; raw material melting; processing of the melt into fibre; settlement of mineral wool and forming of mineral wool mat in the forming chamber; introduction of a binding agent; heat treatment of the mineral wool mat; longitudinal and transversal cutting of the mat into items of specified sizes.
The raw materials are fed from the storage to the crusher. No more than 100 mm raw material lumps are fed to the vibratory screen for screening. The screened raw material is charged to feed bins by conveyors.
From the feed bins the raw material is fed to the skip hoist in batches formed by automatic weighers. The skip hoist charges the raw material into the cupola furnace.
The cupola furnace is designed for production of the mineral melt. SMT-208 water-jacket cupola furnaces are used most often.
A cupola furnace is a shaft kiln. It consists of the main, intermediate and feeding sections, the bottom locking mechanism, overflow launder, spark arrester, steam separation unit, tuyere manifold, melt inlet unit, sections, firing hatch, support frame.
The raw material is charged into the cupola furnace by the tray via the feeding section door. In the non-operating position the tray closes the feed door.
The charge mixture and coke charged into the cupola furnace are fed to the charge mixture distributor and from it to underlying layers to heating zone. Heat exchange between gases being formed in the coke burning zone and charge mixture lumps takes place in the heating zone.
During the cupola furnace process the charge mixture sinks gradually to melting zone. In this zone, the charging mixture exposed to heat emitted during coke burning is melted, and the melt is fed to the lower part of the cupola furnace, i.e. crucible. The mineral melt is discharged from the crucible through the melt outlet unit tap hole to the overflow launder. The overflow launder, in its turn, feeds the mineral melt to fibre-forming mechanisms, most frequently to centrifuge rolls.
As the metal contained in some raw material types is heavier, it settles on the lined bottom of the cupola furnace. As metal is accumulated, it is discharged through a special tap hole located in the rear part of the cupola furnace, it the cupola furnace firing hatch.
To ensure active combustion and to increase SMT-208 cupola furnace capacity, air is blasted to burning area through two tuyere rows of the tuyere belt. Gases being formed during melting flow to the cupola shaft.
Under the feed door there is a device for post-combustion of carbon oxide. It consists of three gas burners. The air necessary for carbon oxide post-combustion is fed into this device.
To clean the fume gases, a wet type spark arrester is used. An evaporating cooling system is used to cool the main section water jacket.
The main section is equipped with a mechanism for opening of the bottoms, a melt outlet unit, a firing latch and a tap hole for discharge of the accumulated metal.
Two rows of tuyeres are located in the water jacket, and the feeding section is equipped with a feed door and a sight cap.
The water jacket cooling evaporating system is equipped with a steam separation device. It consists of a separator tank and a feeding tank sharing a single frame.
The cupola furnace operation is automated. When the cupola furnace operates, the tray is loaded automatically, the temperature of cooling water in the feed tray, protective shield and at water jacket inlet and outlet is monitored. It is equipped with overheating alarm and spark arrester housing temperature monitoring systems. In addition, the respective on-line information about any temperature in the post-combustion and blast air chamber is delivered to the operator, and the consumption of water in the feed tank is regulated. The system is equipped with the remote firing device and the device monitoring presence of flame in post-combustion chamber.
One of the main indices for calculating composition of the charge mixture for production of mineral wool is the acidity index (Ia) which is the ratio of summarised percentage (in terms of weight) of acid oxides (silicon dioxide (SiO2) and aluminium oxide (Al2O3) to the summarised weights of the main oxides – calcium (CaO) and magnesium (MgO) in the raw material.
The acidity index (GOST 4640—84) of the mineral wool shall be no less than 1.2, and for the top quality category 1.4 to 1.5.
As the mineral wool acidity index grows, the water resistance and, consequently, durability of mineral wool increases. However, the mineral wool water resistance depends not only on Ia but also on the quantity of individual oxides.
The mineral wool water resistance is characterised by pH which shall not exceed 7, and for the top quality category 5 (GOST 4640—84).
As a rule, the raw material for mineral wool production is used with corrective additives. To increase Ia of mineral wool, the scrap clay brick, acid rocks, etc. are used. The upper limit (the maximum quantity of acidifier in the charge mixture) is determined based on viscosity modulus (Mv) of the melt. In cupola method of the mineral wool production (without any air heating) the upper limit Mv at which the melting unit capacity is high enough shall not exceed 1.2.
Thus, the composition of the charge mixture for the mineral wool production is determined taking into consideration acidity index, viscosity modulus and water resistance. These indices can be calculated based on chemical composition of the raw material and melt using known chemical methods for determining the mineral wool quality.
Mineral wool (mineral fibre) is used for production of heat- and sound insulation products, and as a heat insulating material in construction and industry for insulating surfaces heated to no more than 700°С. High heat insulating property indices of mineral wool and products based on it, abundance of materials for mineral wool production, relatively low cost determined the wide use of this material in construction.
The latest decade saw consistent growth of demand for high-quality equipment for production of construction materials. Meeting this demand, the Samara Strommashina plant produces a wide range of reliable machines and units which are excellent in performing their process tasks. To simplify the selection of the equipment by our customers, we offer our products both individually, and as the whole turnkey production lines.