The calcium polysulfide aqueous solution, CaSn (also known as lime-sulfur brew or LSB) are an effective source of the active highly dispersed form of sulfur, which has bactericidal, water-repellent, binding, and other valuable properties.
LSB is a 10-30% solution of calcium polysulfide from orange to cherry-red color, which is obtained by boiling an aqueous mixture of ground sulfur and freshly sour lime. Along with calcium polysulphides, by-products, calcium thiosulfate CaS2O3 (23-28%) and calcium carbonate СaCO3 (0.3-1.1%) are formed during the reaction, and 5-11% of unreacted sulfur remains.
Calcium polysulfide solutions of various concentrations are used as a fungicidal acaricidal agent in agriculture, a modifier of building concrete, a convenient means for impregnating building materials (gypsum, concrete, etc.) to impart water repellency to them (instead of uncomfortable high-temperature impregnation with molten sulfur), as self-binder for different fillers (sand, chalk, wood, etc.) used in the preparation of building composite materials with improved properties (sulfur concrete, sulfur asphalt, etc.), for demercurization of industrial premises, etc.
It is important to note that in the practical application of sulfur preparations there are no adverse effects. Moreover, when used in forestry and agriculture, collective gardening, and agriculture, sulfur preparations not only perform their basic functions (protective, as fertilizer), but also replenish soil reserves with elemental sulfur, reducing the increased acidity of the soil.
We have developed a new method for obtaining calcium polysulfide solutions using sulfur and hydrogen sulphide as production waste.
The process is carried out with continuous bubbling of hydrogen sulfide gas into the reaction mass containing quicklime and mechanically activated sulfur in an aqueous medium. The process is carried out under mild conditions (50-800С), the reaction time is 1-2 hours, which allows practically to avoid the formation of by-products (thiosulfate and calcium carbonate) and to increase the content of the main substance in the solution by 2 times compared with the known method of obtaining LSB.
Manufacture of this product is practically wasteless, gas emissions are absent.
The process of obtaining calcium polysulfide solutions is protected by the patent of the Russian Federation №2256602.
It is necessary to store calcium polysulfide solutions without air access (for example, under a layer of mineral oil) in order to avoid decomposition and formation of by-products such as thiosulfate, calcium carbonate and sulfur.