The Research And Development Of Environmental Protecting Technology Of Na₂SiF₆ And Computer Simulation In The Production

Production-cleaning,energy-saving,waster-reducing and environment-protecting modle is the inevitable tendency of chemical development.To develop the production technology of green and environmental protection will get the favour of people.Na₂SiF₆ is an important chemical byproduct in phosphate fertilizers profession.Its traditional technology was made by H₂SiF₆ and saturated NaCl solution in normal temperature.The Hua Mountain Chemical Group Company of Shaanxi produces with this technology,and the waster water is emissed directly since handling difficultily and costing high.The result leads to environment polluted and makes enterprise suffer loss in each aspect. It is extremely urgent to develop the technology of environmental protection of Na₂SiF₆.This paper stands in the existing installation of Na₂SiF₆ of this factory,takes product with Na₂SO₄ replacing NaCl.It goes from laboratory research to industrial test,when discovery problems,and then returns to laboratory to grope as this cycle.Through studying testing the Dry and the Wet method,we eventually definite Wet technology which optimized parameters are dissoluting salt temperature 35℃,salt density 15%,H₂SiF₆ density 8-10%,salt excessive coefficient 1.05-1.1,etc.In the end,we helped the factory realized the replacement of the raw material salt on original installation and the product quality is better than the first-class,the receipt rate goes to 85%exceeding the original raising of 56%,the waster water is recycled completely as filter rushing water and achieved zero emissions.It has developed successfully a technology of environmental protection of Na₂SiF₆.On this foundation,to reduce sewage further,we have overcomed the influence of silica gel and remained Na₂SiF₆ in the laboratory and invented the Mixing method,have realized dissoluting salt by mother liquor,have reduced the possibility of Na₂SO₄·10H₂O that separated out,each cauldron receipt rate is highest to reach over 96%in the base of guaranteeing product quality.This accomplishment is applied for the patent with the claim Number 200810018141.0 and the public Number CN101284669.In the synthetic course of Na₂SiF₆,adding salt speed is the crucial factor that affects product size,quality and receipt rate.This paper firstly simulates the course with Matlab program,makes adding salt controlled by quantitation instead of experience,has very strong guidance for testing and producing,and has established foundation of the computer controling automately in this field.