Abstract: The disclosed method minimizes the tendency of sodium polyborate (the chemical compound obtained from boric acid and sodium sulfate) to set up into a plaster of Paris-like mass during the reaction of concentrated sulfuric acid and a hydrate of sodium tetraborate. By adding a relatively small amount of talc at an early stage in the process of making sodium polyborate, the amount of shear force needed to break up the sodium polyborate product into small particles is greatly decreased. The resulting dry, free-flowing, finely-divided product is useful as, among other things, a pesticide and a fire-retardant agent.

Abstract: For the conversion of sodium tetraborate (e.g. "5 mole borax" or sodium tetraborate pentahydrate) to a solid, particulate mass of flame-retardant chemical, using little or no water, 0.95 to 0.98 mole of sulfuric acid is added to convert the tetraborate to a moist, particulate mixture of boric acid and sodium sulfate. The moist particulate mixture is suitable for imparting flame retardancy to cellulosic insulation; preferably, however, it is first dried to <20 wt.-% moisture.

Abstract: For the conversion of sodium tetraborate (e.g. "5 mole borax" or sodium tetraborate pentahydrate) to a solid, particulate mass of flame-retardant chemical, a slurrying amount of water (e.g. 3-5 moles per mole of tetraborate) is first added, so that a stable slurry can be formed. Then 0.95 to 0.98 mole of sulfuric acid is added to the slurry, and the tetraborate is substantially converted to a moist, particulate mixture of boric acid and sodium sulfate, the water in the slurry having been largely driven off as steam. The moist particulate mixture is suitable for imparting flame retardency to cellulosic insulation; preferably, however, it is first dried to <20 wt.-% moisture.