| 摘要 |
The invention relates to the building material industry, in particular to reprocessing gypsum-containing waste and can be used for producing environmentally friendly gypsum binders, in particular from phosphogypsum. The inventive method for producing a water resistant and environmentally friendly phosphogypsum-based gypsum binder consists in treating a phosphogypsum with sulphuric acid, the concentration of which ranges from 62.5 to 95.0% and which is heated to 40-70°C, in heating the thus obtained suspension to a temperature of 95-105°C, in subsequently holding it at this temperature until the fluoride content thereof becomes equal to or less than 0.05 mass%, in neutralising said suspension in two steps by adding carbonate-containing additives and, afterwards, powder calcium hydroxide therein, in drying the suspension until free water is totally removed, in carrying out autoclave curing, for obtaining a high-strength gypsum binder, or roasting for obtaining an anhydride binder, neutralisation being preceded by blowing off gaseous fluorine with the aid of compressed air and by the fluoride removal, carbon dioxide being removed at the first step of neutralisation. Said invention makes it possible to obtain an environmentally friendly binder exhibiting high water resistance and strength. |
