| Pyrite cinder, a kind of red brown solid waste produced from calcining pyrite in the sulfuric acid production, contains Fe2O3, Fe3O4, metallic sulphate, metallic silicate, metallic oxide, etc...Our country has large-volume production of sulfuric acid, bringing out ahout seven million tons sulfuric acid yearly now, ranked third in the world production. Usually, the pyrite cinder has been disposed by piling up or filling in lowlands or scrap mines, which not only squanders away natural resources, occupies plowland and increases the cost of H2SO4 but also pollutes the soil, water and gas around it greatly. However, the pyrite cinder, a resource that can be reused, contains 20 percent to 60 percent iron and small amount of valuable elements, such as copper, zinc, and trace gold and silver. Comprehensive utilization of pyrite cinder can not only reduce the pollution to environment, save the land but also uplift the utilization ratio of minerals resources.Over several decades, a large number of experts in the fields of science and technology have been carrying out research and practice in an all-round way on the comprehensive utilization of pyrite cinder and gain some achievements. In particular, during the recent years, Polyferric sulfate (ab. PFS), an inorganic polymer flocculants with great efficiency, has been made from pyrite cinder, one of the most prospective ways for comprehensive utilization of pyrite cinder, which makes "treating waste with waste and changing waste into valuable things" possible. This is beneficial both to society and economy. On the other hand, it also has pragmatic importance.Polyferric sulfate is a type of inorganic polymer flocculants with great efficiency and can be expressed as [Fe2(OH)n(SO4)3-n/2]m. Charactered by its remarkable coagulant performance, PFS attracts people's attention. It has a development history over thirty years and solid and liquid productions are available now. But in all methods of making PFS exist the common problems of low utilization ratio of raw material, high cost of energy, long cycle of reaction, great amount of investment, low productive efficiency, complex working procedure of treatments afterwards and toxicity of catalyst, etc. So it is veryessential and prospective to study the new working procedures and methods of preparing PFS and probe into the inner mechanism of synthesization and reaction to prepare PFS with the characters of low cost, excellent effect, stable performance and low toxicity.Combining with a practical scientific research project was commissioned by a enterprise , taking pyrite cinder from the Jinshandian vitriol factory of Wuhan Steel and Mining Industry Corporation as raw material, this paper try to explore the preparing procedure of PFS, an inorganic polymer flocculants with high addictive value, especially probe into the low toxicity catalyst, thereby the nitrite toxicity of production was wiped off, the realm of application in the treatment of water was enlarged. The whole experiment process was divided into three parts - reduction roasting pyrite cinder, vitriol lixiviation and catalytic-oxidation polymerization, the optimum condition was defined in every part, and the production quality and flocculation performance were tested, good results were gained. Furthermore, advanced detection equipments and analysis technique were used to study the main reaction behaviors in the preparation process, so the advancement and rationality of the producing process were achieved, which provided technique support and theoretical foundation to the development of new methods and new processes for further utilizing pyrite cinder. In a word, the method and process of preparing PFS from pyrite cinder was good in this article, which have high utilization ratio of raw material, low cost, short cycle of reaction, and instead of NaNO2, HNO3 acted as catalyst, which makes the toxicity of PFS was eliminated and the performance was better.
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