The composition of glass wool contains SiO2, CaO, MgO, AL2O3,, Na2O, K2O, B2O3 and BaO.
The raw materials for making glass wool include scrap sheet glass, silica sand, feldspar, limestone, dolomite, soda ash, salt cake, borax, etc., which can be selected depending on local resources.
The production process of this line includes raw material preparation, melting, fiberizing, fiber collection, curing, finishing and packaging.
1、Raw material preparation (batching)
Qualified raw materials based on chemical analyses are separately weighed and homogeneously mixed according to the batch formula, and then sent to the furnace bin.
2、Melting
Mixed powder materials (batch) are uniformly fed into the furnace by a batch charger. The batch is melted by high temperature flame in the furnace and homogenized in the refining zone to become homogeneous boron-containing molten glass and then flows to the forehearth.
3、Fiberizing
Molten glass flows through the forehearth to the bushings made of Pt/Rd alloy and kept at constant temperature, from which continuous and stable glass streams flow out and fall down into the spinner. The spinner rotates at high speed and forces molten glass out of the small holes in the sidewall of the spinner by centrifugal force to form primary fibers, which are then attenuated into glass wool by the high temperature and high velocity flame blown from the circular gap of annular burners mounted around the spinner. The jet flame from the burners not only attenuate the fibers, but also maintain the temperature required for the spinner .
To uniformize the upper and lower temperature of the spinner sidewall, internal burners are fitted on the inside of the spinner. In the course of downward movement of fibers, they are further acted by the air-jet fiber attenuator and air cutter to achieve desired effect.
4、Fiber collection
The falling fibers are coated with binder by spraying binder and water. To collect the fibers on the collection conveyor belt to form a blanket, a suction chamber is provided under the conveyor belt, which is connected with suction fans to create negative pressure at the belt surface .To ensure the transverse uniformity of the blanket formed on the belt, fiber distributors are provided at both sides of the collection conveyor .
Waste gas from the fiber collection section is emitted to atmosphere after dust separation by water scrubbers .
Due to the adherence of some binder and fibers to the collection conveyor sides and belt, cleaning and washing devices are provided to clean them off to a collecting pool at the bottom, and waste water containing binder is recycled through filtration and cleaning treatment to realize “zero discharge ”.
The use of above systems can not only decrease air pollution and avoid water pollution, but also recycle much binder so as to reduce the production coat .
5、Curing and cutting
The uncured blanket on the collection conveyor passes a wool lifter and a compacting device before entering the curing oven. The oven contains upper and lower flight conveyors and hot air circulation systems. Here the uncured blanket containing binder is pressed between the flights and dried/cured by hot air to become glass wool blanket or board of certain density and thickness .
The oven is divided into six zones, each of which has an independent hot air circulation system .
For efficient cooling of hot blanket (broad) to facilitate next operations, a cooling conveyor is provided at the exit of the oven.
Depending on the size requirement by customers, the glass wool blanket or board is slit, faced and cut on line. The edge trims are recycled by crushing and sending back by fans to the collection conveyor to be mixed with fresh fibers.
Glass wool blanket is rolled up by a rolling machine and packaged in polyethylene film bag.
Glass wool board is packaged by shrink film packaging machine .
6、Dust collection system
By collecting dust at various spots, the total dust collection efficiency reaches 99％ or more .The dust content in the emitted waste gas is lower than that specified in the corresponding national standard.
7、Water treatment system
Three systems, respectively for sewage, tap water and softened water, are designed for this production line.
8、Binder system
The binder used for this line is composed of phenolic resin, urea, ammonia water, ammonium sulfate, silicone oil, silane and mineral oil, and is prepared by in-pipe mixing method, which is the most advanced technology internationally.The use of this technology can solve those problems which can not be solved by other mixing methods used by general glass wool producers. Firstly, it keeps the resin and additives fresh. Secondly, it minimizes the risk of pipe blocking.Thirdly, it guarantees the chemical properties of mineral oil, avoiding adverse effect on the appearance and feel of glass wool blanket/board caused by the de-emulsification in the case of mixing in tanks.