Fundamental Studies On Resource Utilization Of Solid Waste From Melamine Manufacturing

Melamine, cyanuramide or 2,4,6-triamido-l, 3,5-triazine, is a significant chemical intermediate, which is mainly applied in the production of resin, plastic and coatings etc. As a synthetic resin material, it is a kind of heterocyclic compound whose capacity of production is the biggest in the world today. Presently the main production method of melamine is urea method using water as chilling, purifying and separating agent. Because of hydrolyzation, large quantity of solid waste consisted of melamine, ammeline, ammelide and filter aid will produced in its manufacturing process, which not only pollutes environment and also waste resource. The technology of separating and recovering valuable compositions from solid waste is urgently developed.In term of resource and environment, which are vital issues to national economic sustainable advance, the fundamental research was carried out in this paper to find a way of resource utilization of the solid waste from domestic melamine factories.The first choice of solid waste resource regeneration is the technology of solvent dissolving, crystallizing, separating and recovering. Therefore, based on the principle of the dissolution in the similar material structure, the better solvents were firstly decided through pre-experiment. Filter aid is bergmeal, which doesn't dissolve in organic solvents and water. When the solubilities were measured, the dynamitic method monitoring by laser and computer on line was designed and installed. Using the Chapman's traditional solubility data, the new method's reliability was successfully checked out. Through experiment, the solubility values of the eight systems, melamine-alcohol, melamine-water, melamine-dimethyl sulfoxide, melamine-propiolic alcohol, cyanuric acid-water, cyanuric acid-alcohol, ammeline-alcohol, ammelide-alcohol were obtained in wider temperature range.The experimental data of 142 data points in 8 systems were correlated by the two parameter equation based on molecular thermodynamics model and compared with the back-calculated values, the total mean relative deviation is 4.21%. Correlated with the three-parameter equation put forward by Apelblat et al, the total mean relative deviation is 0.96 %. Taking temperature as input vector and solubility values as output vector to set up the whole BP artificial neural networks of the 8 systems, which uses Leverberg-Marquardt arithmetic, the total mean relative deviation between the 92train and 50 test aggregate samples compared with the experimental data is 0.34 % and 0.75 % respectively.On the basis of Mason's technology, the acid digestion preparation of cyanuric acid was studied further using solid waste from melamine manufacture by waste H2S04 (3%(w) or so) from factories. L9(34) orthogonal test had been done, the low H2SO4 concentration almost amounted to the same yield as the high H2SO4 concentration, and the variance analysis obtained critical factors that effect the yield of cyanuric acid. The BP artificial neural network whose structure was 3 8 8 1 was also applied to pre-estimate the yield of cyanuric acid. The expecting values of the model are in better agreement with the experimental values.