The methods for synthesizing melamine from urea include low-pressure catalytic method and high-pressure non-catalytic method, usually higher than 7MPa. These methods are well known.
High pressure laminate (HPL) consists of 6 to 8 layers of kraft paper, which are glued together and bonded under high pressure and high temperature. Produce a very durable product. The plastic laminate is then adhered to various wood substrates. Melamine is also known as low pressure laminate (LPL), hot melt melamine (TFM) or hot melt laminate (TFL). When 1-2 layers of decorative kraft paper are pressed on the particle board and sealed with resin under pressure and heat, melamine is formed. This material comes in the form of 4×8 panels with various thicknesses such as 1/2 inch, 5/8 inch, 3/4 inch and 1 inch.
Some companies have created color series with matching plastic laminate, melamine and edge tape. This allows the use of melamine in low-contact areas, high-pressure laminates in the remaining areas, and finishing with matching edge tape to produce a perfectly matched and cohesive final result, thereby reducing project costs.
Conventional equipment for synthesizing melamine using a high-pressure non-catalytic method includes a high-pressure section, which is basically limited to a reactor, and is called a melamine reactor. In the melamine reactor, the urea melt feed is converted into crude melamine by adding heat, the added heat coming from, for example, a heating body supplied with molten salt.
In the process of converting urea into melamine, gas (the so-called "exhaust gas") and a variety of by-products (mainly OAT and polycondensate) are also produced mainly composed of ammonia and carbon dioxide. The reaction products (melamine and exhaust gas), by-products and unreacted urea are further processed in the quenching section, which is operated at a significantly lower pressure and temperature. For example, the melamine reactor is operated at about 8 MPa and 380°C, while the quenching section is operated at 2-3 MPa and about 160°C.
In the quenching section, melamine is dissolved in the ammonia solution, and then sent to the subsequent purification section; the exhaust gas is saturated with water and sent to the condensation section, and then recirculated.
Usually, a melamine plant is combined with a urea plant. The urea plant uses NH3 and CO2 as raw materials to produce urea melt feed. It is known to recirculate the exhaust gas generated by the melamine plant to the urea plant; for this purpose, the carbamate solution supplied by the recovery section of the urea plant is usually used for the exhaust gas to condense to produce a solution containing NH3 and CO2, and then the solution is transported back To the urea synthesis circuit.
These conditions are not optimal for recycling to the urea plant: the low pressure does not allow the exhaust gas to be recycled directly to the urea synthesis section; in addition, it is well known that it is not desirable to introduce water into the synthesis loop of the urea plant. Another disadvantage is that the conversion rate of urea to melamine is low, resulting in greater consumption of urea and greater energy consumption in the downstream section.
Abundant urea resources give China a unique advantage in melamine production.
China is the world's largest urea producer, with large output and low price. Even under the background of high tariffs to suppress urea exports, the annual export volume of urea still reaches (300 to 7) million tons.
There are many types of our melamine powder. There are melamine 99.9%, melamine 99.8%, melamine 99.5% and high-pressure melamine for your choice. If you have any needs, you can contact us.