Preparation method and system of sustained-release silicon-potassium fertilizer

The invention relates to the field of waste resource comprehensive utilization, and specifically relates to a preparation method and a preparation system of a sustained-release silicon-potassium fertilizer. The method is realized in a slag pot, and comprises the following steps: 1, preparation is carried out, wherein high-temperature blast furnace slag enters the slag pot (3); a modifier K2SO4 is added into a pressure vessel (9); and a spray gun (5) is inserted into the blast furnace slag in the slag pot (3); 2, a synthesis reaction is carried out, wherein the modifier K2SO4 is sprayed into the blast furnace slag in the slag pot (3) through the spray gun (5) with carrier gas (12); the modifier is uniformly mixed with the blast furnace slag, and is heated and molten; K2SO4 is decomposed into K2O and SO3, wherein K2O and SiO2 in the blast furnace slag are synthesized into a K2O.nSiO2 sustained-release compound; and 3, product collection is carried out, wherein SO3 gas enters a water tank (8) and is subjected to a chemical reaction with water, such that a H2SO4 solution is obtained; and the K2O.nSiO2 sustained-release compound is cooled, crushed and bagged. According to the invention, waste resources are utilized, energy is saved, and the environment is protected. The production cost is low, and the process is simple and is easy to realize.